Showing posts with label numericals. Show all posts
Showing posts with label numericals. Show all posts

Monday 23 December 2013

Atmospheric electricity - class 12 notes with numercals

Atmospheric Electricity: Phenomena, Measurements, and Applications.


Atmospheric Electricity: Phenomena, Measurements, and Applications.  Atmospheric electricity refers to the electrical properties and phenomena that occur in the Earth's atmosphere. It is a complex and fascinating field of study that has captured the attention of scientists for over a century. The Earth's atmosphere is constantly charged due to the interaction of the Sun's radiation, cosmic rays, and thunderstorm activity. This has led to the discovery of many important phenomena, including lightning, the ionosphere, and the aurora borealis. Atmospheric electricity has practical applications in areas such as weather forecasting, radio communication, and the design of lightning protection systems. In this article, we will explore the sources of atmospheric electricity, the different atmospheric electrical phenomena, the measurements used to study it, and its practical applications. We will also answer some frequently asked questions about atmospheric electricity  Table of Contents: Atmospheric Electricity: Phenomena, Measurements, and Applications.  • Introduction to Atmospheric Electricity  • Sources of Atmospheric Electricity  • Atmospheric Electrical Phenomena  • Lightning  • Thunderstorms  • Atmospheric Electrical Measurements  • Applications of Atmospheric Electricity  • Frequently Asked Questions  1. Introduction to Atmospheric Electricity  Atmospheric electricity refers to the electrical properties and phenomena that occur in the Earth's atmosphere. The Earth's atmosphere is constantly charged due to the interaction of the Sun's radiation, cosmic rays, and thunderstorm activity. Atmospheric electricity has been studied for over a century and has led to the discovery of many important phenomena, including lightning, the ionosphere, and the aurora borealis.  2. Sources of Atmospheric Electricity  The primary sources of atmospheric electricity are the Sun's radiation, cosmic rays, and thunderstorm activity. The Sun's radiation causes the ionization of gases in the upper atmosphere, leading to the formation of the ionosphere. Cosmic rays, which are high-energy particles from space, also contribute to the ionization of the atmosphere. Thunderstorm activity causes the buildup of electric charges in the lower atmosphere, leading to lightning and other electrical phenomena.  3. Atmospheric Electrical Phenomena  Atmospheric electrical phenomena include lightning, thunderstorms, sprites, and elves. Lightning is the most well-known and dramatic atmospheric electrical phenomenon. It is caused by the buildup of electric charges in the atmosphere, leading to a discharge of electricity between the clouds and the ground. Thunderstorms are also a common atmospheric electrical phenomenon and are characterized by the buildup of electric charges in the lower atmosphere, leading to thunder and lightning.  Sprites and elves are less well-known atmospheric electrical phenomena. Sprites are large-scale electrical discharges that occur high in the atmosphere, above thunderstorms. Elves are electromagnetic pulses that occur in the ionosphere, caused by the interaction of lightning discharges with the ionosphere.  4. Lightning  Lightning is a natural electrical discharge that occurs in the atmosphere. It is caused by the buildup of electric charges in the atmosphere, which leads to a discharge of electricity between the clouds and the ground. Lightning can be very dangerous and can cause injury or death to people and damage to buildings and other structures.  There are several types of lightning, including cloud-to-ground lightning, intra-cloud lightning, and cloud-to-cloud lightning. Cloud-to-ground lightning is the most well-known type and occurs when a discharge of electricity travels from the cloud to the ground. Intra-cloud lightning occurs entirely within the cloud, while cloud-to-cloud lightning occurs between different clouds.  5. Thunderstorms  Thunderstorms are a type of weather phenomenon characterized by the buildup of electric charges in the atmosphere. Thunderstorms can produce lightning, thunder, heavy rain, strong winds, and even tornadoes. Thunderstorms can be very dangerous and can cause property damage and loss of life.  Thunderstorms are caused by the interaction of warm and cold air masses. Warm air rises, and as it does, it cools and condenses into clouds. The updrafts within the cloud cause the buildup of electric charges, which can lead to lightning and thunder.  6. Atmospheric Electrical Measurements  Atmospheric electrical measurements are used to study the electrical properties of the atmosphere. These measurements include electric field measurements, atmospheric conductivity measurements, and measurements of atmospheric ionization.  Electric field measurements are used to measure the strength and direction of the electric field in the atmosphere. Atmospheric conductivity measurements are used to measure the ability of the atmosphere to conduct electricity. Measurements of atmospheric ionization are used to measure the concentration of ions in the atmosphere.  7. Applications of Atmospheric Electricity  Atmospheric electricity has many practical applications. For example, it is used in the design of lightning protection systems for buildings and other structures. Atmospheric electricity is also used in the    Continue  study of the ionosphere, which is important for radio communication and satellite navigation. Additionally, atmospheric electrical measurements can be used to study weather patterns and predict severe weather events.  8. Frequently Asked Questions  Q: Can atmospheric electricity be used as a source of energy? A: While atmospheric electricity is a source of energy, it is not currently practical to harness it for energy production due to the high cost and low efficiency of existing technologies.  Q: How is lightning formed? A: Lightning is formed by the buildup of electric charges in the atmosphere, which leads to a discharge of electricity between the clouds and the ground.  Q: What is the ionosphere? A: The ionosphere is a region of the Earth's upper atmosphere that is ionized by solar radiation. It plays an important role in radio communication and satellite navigation.  Q: What is atmospheric conductivity? A: Atmospheric conductivity is a measure of the ability of the atmosphere to conduct electricity. It is influenced by factors such as temperature, humidity, and ionization.  Q: How can atmospheric electricity be measured? A: Atmospheric electricity can be measured using a variety of instruments, including electric field meters, ion counters, and atmospheric conductivity meters. These instruments are used to measure the electric field, ionization, and conductivity of the atmosphere.  Q: Is atmospheric electricity dangerous? A: Atmospheric electricity can be dangerous, particularly during thunderstorms and lightning strikes. It is important to take precautions to protect yourself during severe weather events.  Q: What are sprites and elves? A: Sprites and elves are atmospheric electrical phenomena that occur high in the atmosphere. Sprites are large-scale electrical discharges, while elves are electromagnetic pulses caused by the interaction of lightning with the ionosphere.

Atmospheric Electricity: Phenomena, Measurements, and Applications.

Atmospheric electricity refers to the electrical properties and phenomena that occur in the Earth's atmosphere. It is a complex and fascinating field of study that has captured the attention of scientists for over a century. The Earth's atmosphere is constantly charged due to the interaction of the Sun's radiation, cosmic rays, and thunderstorm activity. This has led to the discovery of many important phenomena, including lightning, the ionosphere, and the aurora borealis. Atmospheric electricity has practical applications in areas such as weather forecasting, radio communication, and the design of lightning protection systems. In this article, we will explore the sources of atmospheric electricity, the different atmospheric electrical phenomena, the measurements used to study it, and its practical applications. We will also answer some frequently asked questions about atmospheric electricity




Table of Contents: Atmospheric Electricity: Phenomena, Measurements, and Applications.


• Introduction to Atmospheric Electricity

• Sources of Atmospheric Electricity

• Atmospheric Electrical Phenomena

• Lightning

• Thunderstorms

• Atmospheric Electrical Measurements

• Applications of Atmospheric Electricity

• Frequently Asked Questions

1. Introduction to Atmospheric Electricity


Atmospheric electricity refers to the electrical properties and phenomena that occur in the Earth's atmosphere. The Earth's atmosphere is constantly charged due to the interaction of the Sun's radiation, cosmic rays, and thunderstorm activity. Atmospheric electricity has been studied for over a century and has led to the discovery of many important phenomena, including lightning, the ionosphere, and the aurora borealis.

2. Sources of Atmospheric Electricity


The primary sources of atmospheric electricity are the Sun's radiation, cosmic rays, and thunderstorm activity. The Sun's radiation causes the ionization of gases in the upper atmosphere, leading to the formation of the ionosphere. Cosmic rays, which are high-energy particles from space, also contribute to the ionization of the atmosphere. Thunderstorm activity causes the buildup of electric charges in the lower atmosphere, leading to lightning and other electrical phenomena.

3. Atmospheric Electrical Phenomena


Atmospheric electrical phenomena include lightning, thunderstorms, sprites, and elves. Lightning is the most well-known and dramatic atmospheric electrical phenomenon. It is caused by the buildup of electric charges in the atmosphere, leading to a discharge of electricity between the clouds and the ground. Thunderstorms are also a common atmospheric electrical phenomenon and are characterized by the buildup of electric charges in the lower atmosphere, leading to thunder and lightning.

Sprites and elves are less well-known atmospheric electrical phenomena. Sprites are large-scale electrical discharges that occur high in the atmosphere, above thunderstorms. Elves are electromagnetic pulses that occur in the ionosphere, caused by the interaction of lightning discharges with the ionosphere.

4. Lightning


Lightning is a natural electrical discharge that occurs in the atmosphere. It is caused by the buildup of electric charges in the atmosphere, which leads to a discharge of electricity between the clouds and the ground. Lightning can be very dangerous and can cause injury or death to people and damage to buildings and other structures.

There are several types of lightning, including cloud-to-ground lightning, intra-cloud lightning, and cloud-to-cloud lightning. Cloud-to-ground lightning is the most well-known type and occurs when a discharge of electricity travels from the cloud to the ground. Intra-cloud lightning occurs entirely within the cloud, while cloud-to-cloud lightning occurs between different clouds.

5. Thunderstorms


Thunderstorms are a type of weather phenomenon characterized by the buildup of electric charges in the atmosphere. Thunderstorms can produce lightning, thunder, heavy rain, strong winds, and even tornadoes. Thunderstorms can be very dangerous and can cause property damage and loss of life.

Thunderstorms are caused by the interaction of warm and cold air masses. Warm air rises, and as it does, it cools and condenses into clouds. The updrafts within the cloud cause the buildup of electric charges, which can lead to lightning and thunder.

6. Atmospheric Electrical Measurements

Atmospheric electrical measurements are used to study the electrical properties of the atmosphere. These measurements include electric field measurements, atmospheric conductivity measurements, and measurements of atmospheric ionization.

Electric field measurements are used to measure the strength and direction of the electric field in the atmosphere. Atmospheric conductivity measurements are used to measure the ability of the atmosphere to conduct electricity. Measurements of atmospheric ionization are used to measure the concentration of ions in the atmosphere.

7. Applications of Atmospheric Electricity


Atmospheric electricity has many practical applications. For example, it is used in the design of lightning protection systems for buildings and other structures. Atmospheric electricity is also used in the study of the ionosphere, which is important for radio communication and satellite navigation. Additionally, atmospheric electrical measurements can be used to study weather patterns and predict severe weather events.

The earth’s atmosphere extends to about 300 Km above the earth surface. The atmosphere is divided in four layers.
   300 km               400°C                                                                                     d4 = d/1010
Ionosphere                               Good Conductor                                                
Text Box: ConductivityText Box: Increases     80 km               -90°C                                                                                     d= d/105
Mesosphere                                                                                                               
                                                        
     50 Km               10°C                                                                                      d2 = d/1000
Stratosphere                                
                                                            
     12 km                -50°C                                                                                    d1 = d/10
Troposphere                             Poor Conductor
                      Temp = 15°C                                              density of air d = 1.29kg/m3    

Electrical properties of the atmosphere: -
(1)    The electrical phenomena in atmosphere take place between the earth surface and top of stratosphere. The 50 Km thick layers is like a blanket enveloping the earth.

(2)  An electric field 100 V/m is there downwards all over the earth, at ground level.

8. Frequently Asked Questions: FAQs


Q: Can atmospheric electricity be used as a source of energy? A: While atmospheric electricity is a source of energy, it is not currently practical to harness it for energy production due to the high cost and low efficiency of existing technologies.

Q: How is lightning formed? A: Lightning is formed by the buildup of electric charges in the atmosphere, which leads to a discharge of electricity between the clouds and the ground.

Q: What is the ionosphere? A: The ionosphere is a region of the Earth's upper atmosphere that is ionized by solar radiation. It plays an important role in radio communication and satellite navigation.

Q: What is atmospheric conductivity? A: Atmospheric conductivity is a measure of the ability of the atmosphere to conduct electricity. It is influenced by factors such as temperature, humidity, and ionization.

Q: How can atmospheric electricity be measured? A: Atmospheric electricity can be measured using a variety of instruments, including electric field meters, ion counters, and atmospheric conductivity meters. These instruments are used to measure the electric field, ionization, and conductivity of the atmosphere.

Q: Is atmospheric electricity dangerous? A: Atmospheric electricity can be dangerous, particularly during thunderstorms and lightning strikes. It is important to take precautions to protect yourself during severe weather events.

Q: What are sprites and elves? A: Sprites and elves are atmospheric electrical phenomena that occur high in the atmosphere. Sprites are large-scale electrical discharges, while elves are electromagnetic pulses caused by the interaction of lightning with the ionosphere.
          


Sunday 22 December 2013

GRAVITATION : Introduction, Detailed description, numericals, FAQs

Gravitations introduction, detailed explanation with equations, numericals, FAQsGRAVITATION : Introduction, Detailed description, numericals, FAQs


Introduction:


Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun. Earth's gravity is what keeps you on the ground and what makes things fall.

Detailed Explanation with Equations:


Gravity is described by the law of universal gravitation, which states that every point mass attracts every other point mass by a force acting along the line intersecting both points. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between them. The equation for the law of universal gravitation is given by:

F = G (m1m2/r²)

Where F is the force of gravity between the two objects, m1 and m2 are the masses of the two objects, r is the distance between the two objects, and G is the gravitational constant.

The gravitational constant, denoted by G, is a fundamental constant of nature that appears in the law of universal gravitation. Its value is approximately 6.674 x 10^-11 N·m²/kg².

The force of gravity is always attractive, which means that it pulls objects together. The magnitude of the force depends on the masses of the objects and the distance between them. If the masses of the objects are large, the force of gravity between them is also large. If the distance between the objects is large, the force of gravity between them is weaker.

Numericals:


Here are a few numerical examples to illustrate the use of the law of universal gravitation:

• Calculate the force of gravity between two objects with masses of 10 kg and 20 kg that are separated by a distance of 5 meters.

Solution:

F = G (m1m2/r²) F = 6.674 x 10^-11 N·m²/kg² (10 kg x 20 kg)/(5 m)² F = 2.004 x 10^-9 N

Therefore, the force of gravity between the two objects is 2.004 x 10^-9 N.

• A 1,000-kg satellite is in orbit around Earth at an altitude of 500 km. What is the force of gravity on the satellite?

Solution:

The distance between the satellite and the center of Earth is equal to the sum of the radius of Earth (6,371 km) and the altitude of the satellite (500 km).

r = 6,371 km + 500 km = 6,871 km = 6,871,000 meters

The mass of Earth is 5.97 x 10^24 kg.

F = G (m1m2/r²) F = 6.674 x 10^-11 N·m²/kg² (1,000 kg x 5.97 x 10^24 kg)/(6,871,000 m)² F = 8,869 N

Therefore, the force of gravity on the satellite is 8,869 N.

Problem: A planet of mass 6 x 10^24 kg has a radius of 6.4 x 10^6 m. A satellite of mass 1000 kg is orbiting around it at a height of 8000 km above the surface of the planet. Calculate: (a) The acceleration due to gravity on the surface of the planet. (b) The speed of the satellite in its orbit. (c) The time period of the satellite's orbit.

Solution: (a) The acceleration due to gravity on the surface of the planet can be calculated using the formula:

g = G M / R^2

where g is the acceleration due to gravity, G is the universal gravitational constant, M is the mass of the planet, and R is the radius of the planet.

Plugging in the given values, we get:

g = (6.67 x 10^-11 Nm^2/kg^2) x (6 x 10^24 kg) / (6.4 x 10^6 m)^2 g = 9.81 m/s^2

Therefore, the acceleration due to gravity on the surface of the planet is 9.81 m/s^2.

(b) The speed of the satellite in its orbit can be calculated using the formula:

v = √(G M / r)

where v is the speed of the satellite, G is the universal gravitational constant, M is the mass of the planet, and r is the distance of the satellite from the center of the planet.

The distance of the satellite from the center of the planet is:

r = R + h = (6.4 x 10^6 m) + (8000 km) = 6.4 x 10^6 m + 8 x 10^6 m = 1.44 x 10^7 m

Plugging in the given values, we get:

v = √[(6.67 x 10^-11 Nm^2/kg^2) x (6 x 10^24 kg) / (1.44 x 10^7 m)] v = 10,968 m/s (approx.)

Therefore, the speed of the satellite in its orbit is approximately 10,968 m/s.

(c) The time period of the satellite's orbit can be calculated using the formula:

T = 2πr / v

where T is the time period of the orbit, r is the distance of the satellite from the center of the planet, and v is the speed of the satellite.

Plugging in the values we have calculated, we get:

T = 2π x (1.44 x 10^7 m) / (10,968 m/s) T = 13,500 seconds (approx.)

Therefore, the time period of the satellite's orbit is approximately 13,500 seconds or 3.75 hours.

Problem: Two objects of masses 10 kg and 5 kg are placed at a distance of 2 m from each other. Calculate the gravitational force of attraction between them. Also, calculate the acceleration due to gravity experienced by each of the objects due to this force.

Solution: The gravitational force of attraction between the two objects can be calculated using the formula:

F = G (m1m2) / r^2

where F is the force of attraction, G is the universal gravitational constant, m1 and m2 are the masses of the two objects, and r is the distance between the centers of the two objects.

Plugging in the given values, we get:

F = (6.67 x 10^-11 Nm^2/kg^2) x (10 kg) x (5 kg) / (2 m)^2 F = 8.34 x 10^-10 N

Therefore, the gravitational force of attraction between the two objects is 8.34 x 10^-10 N.

The acceleration due to gravity experienced by each of the objects due to this force can be calculated using the formula:

a = F / m

where a is the acceleration due to gravity, F is the gravitational force of attraction, and m is the mass of the object.

For the 10 kg mass, the acceleration due to gravity is:

a = (8.34 x 10^-10 N) / (10 kg) a = 8.34 x 10^-11 m/s^2

For the 5 kg mass, the acceleration due to gravity is:

a = (8.34 x 10^-10 N) / (5 kg) a = 1.67 x 10^-9 m/s^2

Therefore, the acceleration due to gravity experienced by the 10 kg object is 8.34 x 10^-11 m/s^2 and the acceleration due to gravity experienced by the 5 kg object is 1.67 x 10^-9 m/s^2.

• Two objects of masses 5 kg and 10 kg are placed at a distance of 4 m from each other. Calculate the gravitational force of attraction between them.

Solution: Using the formula F = G (m1m2) / r^2, we get:

F = (6.67 x 10^-11 Nm^2/kg^2) x (5 kg) x (10 kg) / (4 m)^2 F = 8.34 x 10^-11 N

Therefore, the gravitational force of attraction between the two objects is 8.34 x 10^-11 N.

• A planet has a mass of 6 x 10^24 kg and a radius of 6.4 x 10^6 m. Calculate the acceleration due to gravity on the surface of the planet.

Solution: Using the formula g = G M / R^2, we get:

g = (6.67 x 10^-11 Nm^2/kg^2) x (6 x 10^24 kg) / (6.4 x 10^6 m)^2 g = 9.81 m/s^2

Therefore, the acceleration due to gravity on the surface of the planet is 9.81 m/s^2.

• A satellite of mass 1000 kg is in orbit around a planet with a mass of 6 x 10^24 kg and a radius of 6.4 x 10^6 m. The satellite is orbiting at a height of 8000 km above the surface of the planet. Calculate the speed of the satellite in its orbit.

Solution: The distance of the satellite from the center of the planet is:

r = R + h = (6.4 x 10^6 m) + (8000 km) = 6.4 x 10^6 m + 8 x 10^6 m = 1.44 x 10^7 m

Using the formula v = √(G M / r), we get:

v = √[(6.67 x 10^-11 Nm^2/kg^2) x (6 x 10^24 kg) / (1.44 x 10^7 m)] v = 10,968 m/s (approx.)

Therefore, the speed of the satellite in its orbit is approximately 10,968 m/s.

• A planet has a mass of 2 x 10^23 kg and a radius of 4000 km. Calculate the escape velocity from the surface of the planet.

Solution: Using the formula v = √(2GM/R), we get:

v = √[(2 x 6.67 x 10^-11 Nm^2/kg^2 x 2 x 10^23 kg) / (4000 km + 6.4 x 10^6 m)] v = 4.18 km/s (approx.)

Therefore, the escape velocity from the surface of the planet is approximately 4.18 km/s.

• Two objects of masses 2 kg and 4 kg are placed at a distance of 3 m from each other. Calculate the gravitational potential energy of the system.

Solution: Using the formula U = -G(m1m2)/r, we get:

U = -(6.67 x 10^-11 Nm^2/kg^2) x (2 kg) x (4 kg) / (3 m) U = -1.78 x 10^-10 J

Therefore, the gravitational potential energy of the system is -1.78 x 10^-10 J.

• A planet of mass 3 x 10^24 kg has a moon of mass 5 x 10^22 kg orbiting around it in a circular orbit at a distance of 4 x 10^5 km. Calculate the speed of the moon in its orbit.

Solution: Using the formula v = √(GM/r), we get:

v = √[(6.67 x 10^-11 Nm^2/kg^2 x 3 x 10^24 kg) / (4 x 10^5 km + 6.4 x 10^6 m)] v = 1024 m/s (approx.)

Therefore, the speed of the moon in its orbit is approximately 1024 m/s.

FAQs:


Q1. What is the difference between mass and weight?

Ans. Mass is a measure of the amount of matter in an object, while weight is a measure of the force of gravity on an object. Mass is measured in kilograms (kg), while weight is measured in newtons (N).

Q2. What is the acceleration due to gravity on Earth?

Ans. The acceleration due to gravity on Earth is approximately 9.8 m/s².

Q3. What is the difference between the gravitational force and the electrostatic force?

Ans. The gravitational force is the force of attraction between any two objects with mass, while the electrostatic force is the force of attraction or repulsion between two charged objects.

Q4. What is the gravitational field?

Ans. The gravitational field is the region around a mass where another mass would experience a force due to gravity. It is a vector field, meaning that at every point in space, there is a gravitational force acting in a certain direction.

Q5. What is escape velocity?

Ans. Escape velocity is the minimum velocity needed to escape the gravitational field of a planet or other celestial body. It is the velocity at which the kinetic energy of an object is equal to its potential energy due to gravity. The formula for escape velocity is given by:

v = sqrt(2GM/r)

Where v is the escape velocity, G is the gravitational constant, M is the mass of the planet or celestial body, and r is the distance from the center of the planet or celestial body.

Q6. What is the difference between gravitational potential energy and gravitational potential?

Ans. Gravitational potential energy is the energy an object possesses due to its position in a gravitational field, while gravitational potential is the potential energy per unit mass at a point in a gravitational field. Gravitational potential is a scalar quantity, while gravitational potential energy is a scalar quantity for a single object, but a vector quantity when considering the potential energy of a system of objects.

Q7. What is the difference between the weight of an object and the force of gravity acting on it?

Ans. The weight of an object is the force with which the object is pulled towards the center of the Earth due to gravity. It is equal to the mass of the object multiplied by the acceleration due to gravity. The force of gravity acting on an object is the force that the Earth exerts on the object due to its mass. It is equal to the product of the mass of the object and the gravitational field strength at the location of the object.

Q8. What is the significance of the gravitational constant?

Ans. The gravitational constant is a fundamental constant of nature that relates the strength of the gravitational force to the masses of the objects and the distance between them. It allows us to calculate the force of gravity between any two objects in the universe. The value of the gravitational constant is crucial in many areas of physics, including astronomy, cosmology, and particle physics.

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GRAVITATION


1.                              In The universe every mass attracts the other mass by a force, which is known as gravitational force.
2.                              Earth also attracts the other masses and the force of attraction of earth is said to be force of gravity.
Newton’s Law of Gravitation: -
This law is for the force of attraction between any two-point masses.
Consider two masses m1 & m2 , kept at a distance of  r  in between then the force acting between then will be   ‘F’ which is given as
<![endif]-->                             F                           F
               m1                                                                  m2

                                        r
1        The force of attraction is proportional to product of masses say
F  
<![endif]--> m1 m2
      2.   The force of attraction is inversely proportional to the square of distance between the masses. i.e.





                                           
3.    The gravitational force is always attractive force.






4.    The gravitational force will be along the line joining the masses.  So,
                          
       G  =  Gravitational Constant having same value in the complete universe.
       G  =    6.67 x 10 –11  Nm2     kg –2                                                  [G]  =  [M-1 L3 T-2]
       F   =    6.67 x 10 –11
Definition of unit mass or one kg   :-       
            If   m1 =  m2   =   1 kg ,       r  =   1 m
            F = 6.67 x 10-11  Nm2 kg-2

It two equal masses are kept at a distance of –1m apart and force acting between them is 6.67 x 10-11 N, then each mass will be unit mass of 1 kg.


MAGNETIC EFFECT OF ELECTRIC CURRENT: Short notes numericals and equations

MAGNETIC  EFFECT   OF  ELECTRIC  CURRENT: Short notes numericals and equations


MAGNETIC   EFFECT   OF   ELECTRIC   CURRENT: Short notes numericals and equations

Introduction:


Magnetism is one of the most intriguing phenomena in nature, and it has been studied by scientists for centuries. Magnetic effects are pervasive in our daily lives, from the simple magnets on our refrigerator doors to the more complex magnetic fields that are generated by the Earth's core. In this article, we will explore the magnetic effect and related topics, including the fundamental equations that describe magnetic behavior.

Magnetic Field:


A magnetic field is a region in space where magnetic forces are observed. The magnetic field is a vector field that describes the direction and magnitude of the force experienced by a magnetic dipole placed in the field. Magnetic fields are produced by moving electric charges, such as electrons. The strength of the magnetic field at a given point is given by the magnetic field strength or magnetic flux density, B. The unit of B is the tesla (T), named after the famous inventor Nikola Tesla.

Magnetic Force:


A magnetic field exerts a force on a magnetic dipole placed within it. The magnetic force is given by the following equation:

F = qv x B

Where F is the force vector, q is the charge of the particle, v is the velocity vector of the particle, and B is the magnetic field vector. The direction of the force vector is perpendicular to both the velocity vector and the magnetic field vector. The magnitude of the force is given by F = qvBsinθ, where θ is the angle between the velocity vector and the magnetic field vector.

Magnetic Dipole Moment:


A magnetic dipole is a pair of equal and opposite magnetic charges separated by a distance d. The magnetic dipole moment, m, is a measure of the strength and direction of the magnetic dipole. It is defined as the product of the magnitude of the magnetic charge and the separation between the charges, i.e., m = qd.

Magnetic Induction:


When a magnetic field is applied to a material, it induces a magnetization within the material. The induced magnetization is proportional to the applied magnetic field, and the proportionality constant is called the magnetic susceptibility, χ. The magnetic susceptibility is a dimensionless quantity and is usually expressed in units of volume per unit volume (e.g., m3/kg). The magnetic susceptibility is positive for diamagnetic materials, negative for paramagnetic materials, and very large for ferromagnetic materials.

Magnetic Materials:


Materials can be classified into three categories based on their magnetic properties: diamagnetic, paramagnetic, and ferromagnetic. Diamagnetic materials are weakly repelled by magnetic fields and have a negative magnetic susceptibility. Examples of diamagnetic materials include copper, silver, and gold. Paramagnetic materials are weakly attracted by magnetic fields and have a positive magnetic susceptibility. Examples of paramagnetic materials include aluminum, platinum, and manganese. Ferromagnetic materials are strongly attracted by magnetic fields and have a very large magnetic susceptibility. Examples of ferromagnetic materials include iron, nickel, and cobalt.

Maxwell's Equations:


Maxwell's equations describe the behavior of electric and magnetic fields in space. They are a set of four partial differential equations that relate the electric and magnetic fields to their sources. The equations are named after James Clerk Maxwell, who formulated them in the 19th century. The equations are as follows:

• Gauss's law for electric fields:

∇ ⋅ E = ρ/ε0

Where E is the electric field, ρ is the charge density, and ε0 is the electric constant.

• Gauss's law for magnetic fields:

∇ ⋅ B = 0

Where B is the magnetic field.

• Faraday's law of electromagnetic induction:

∇ × E = - ∂B/∂t

Where ∂B/∂t is the time derivative of the magnetic field, and the cross product denotes the curl of the electric field.

• Ampere's law with Maxwell's correction:

∇ × B = μ0(j + ε0∂E/∂t)

Where j is the current density, μ0 is the magnetic constant, and the curl of the magnetic field is equal to the sum of the current density and the time derivative of the electric field.

These four equations describe the behavior of electric and magnetic fields in space and their interaction with charges and currents. They are fundamental to understanding the behavior of electromagnetic waves, which are the basis of many modern technologies.

Magnetic Materials and Hysteresis:


Magnetic materials exhibit a phenomenon called hysteresis, where the magnetization of the material lags behind changes in the applied magnetic field. Hysteresis is caused by the alignment of magnetic domains within the material. These domains are regions of the material where the magnetic moments of the atoms are aligned in the same direction. When a magnetic field is applied, the domains align with the field, and the material becomes magnetized. When the field is removed, the domains retain their alignment, and the material remains magnetized. The amount of magnetization depends on the strength of the applied magnetic field.

Hysteresis can be represented graphically by a hysteresis loop. The loop shows the relationship between the magnetic field strength and the magnetization of the material. As the magnetic field strength increases, the magnetization of the material increases until it reaches saturation. When the field is reduced, the magnetization lags behind, and the material retains some magnetization even when the field is zero.

Applications of Magnetic Effect:


Magnetic effects have many applications in science and technology. Here are some of the most important applications:

• Magnetic storage: Magnetic materials are used to store data in hard drives, floppy disks, and magnetic tape. The magnetic domains within the material represent the 0s and 1s of digital data.

• Magnetic levitation: Magnetic levitation, or maglev, uses magnetic fields to suspend an object in the air. Maglev trains are a promising form of transportation that can travel at high speeds with minimal friction.

• Magnetic resonance imaging (MRI): MRI is a medical imaging technique that uses magnetic fields and radio waves to create images of the inside of the body. MRI is non-invasive and does not use ionizing radiation, making it a safer alternative to X-rays and CT scans.

• Electric motors: Electric motors use magnetic fields to convert electrical energy into mechanical energy. The interaction between the magnetic field and the current in the motor produces a force that rotates the motor.

Conclusion:


In conclusion, the magnetic effect is a fascinating phenomenon that has many important applications in science and technology. Magnetic fields, forces, and materials can be described by a set of fundamental equations known as Maxwell's equations. Understanding the magnetic effect is essential for many fields, including physics, engineering, and medicine. By exploring the properties and behavior of magnetic fields, we can develop new technologies that improve our lives and advance our understanding of the universe.

Numericals for magnetic effects


• A wire carrying a current of 2 A is placed in a magnetic field of 0.5 T. What is the force on the wire if it is perpendicular to the field?

• A coil with 100 turns is placed in a magnetic field of 0.2 T. If the coil has an area of 0.1 m2 and is perpendicular to the field, what is the magnetic flux through the coil?

• A solenoid with 500 turns has a length of 0.2 m and a radius of 0.01 m. If a current of 5 A flows through the solenoid, what is the magnetic field at the center of the solenoid?

• A charged particle with a charge of 2 C and a velocity of 5 m/s enters a magnetic field of 0.1 T at an angle of 30° to the field. What is the force on the particle?

• A transformer has 1000 turns in the primary coil and 500 turns in the secondary coil. If the voltage in the primary coil is 100 V, what is the voltage in the secondary coil?

• A wire carrying a current of 3 A is wrapped around a soft iron core with a permeability of 1000. If the coil has 100 turns and a radius of 0.05 m, what is the magnetic field inside the core?

• A wire carrying a current of 4 A is bent into a loop with a radius of 0.1 m. If the loop is placed in a magnetic field of 0.3 T, what is the torque on the loop if the field is perpendicular to the plane of the loop?

• A particle with a charge of -1 μC and a velocity of 10 m/s enters a magnetic field of 0.5 T at an angle of 45° to the field. What is the radius of the particle's path?

• A wire carrying a current of 2 A is placed in a magnetic field of 0.4 T. If the wire is perpendicular to the field and has a length of 0.2 m, what is the force on the wire?

• A transformer has 500 turns in the primary coil and 2000 turns in the secondary coil. If the current in the primary coil is 5 A, what is the current in the secondary coil?

• A solenoid with 1000 turns has a length of 0.3 m and a radius of 0.02 m. If a current of 10 A flows through the solenoid, what is the magnetic field at a point on the axis of the solenoid 0.1 m from the center?

• A charged particle with a charge of 3 C and a velocity of 2 m/s enters a magnetic field of 0.2 T at an angle of 60° to the field. What is the force on the particle?

• A wire carrying a current of 6 A is wrapped around a soft iron core with a permeability of 500. If the coil has 50 turns and a radius of 0.1 m, what is the magnetic field inside the core?

• A wire carrying a current of 5 A is bent into a loop with a radius of 0.2 m. If the loop is placed in a magnetic field of 0.2 T, what is the torque on the loop if the field is perpendicular to the plane of the loop?

• A transformer has 200 turns in the primary coil and 1000 turns in the secondary coil. If the voltage in the primary coil is 120 V, what is the voltage in the secondary coil?

• A particle with a charge of 2 μC and a velocity of 8 m/s enters a magnetic field of 0.1 T at an angle of 90° to the field. What is the force on the particle?

• A solenoid with 200 turns has a length of 0.4 m and a radius of 0.03 m. If a current of 2 A flows through the solenoid, what is the magnetic field at a point on the axis of the solenoid 0.1 m from the center?

• A wire carrying a current of 7 A is placed in a magnetic field of 0.6 T. If the wire is perpendicular to the field and has a length of 0.3 m, what is the force on the wire?

• A transformer has 500 turns in the primary coil and 100 turns in the secondary coil. If the voltage in the secondary coil is 20 V, what is the voltage in the primary coil?

• A charged particle with a charge of -3 C and a velocity of 6 m/s enters a magnetic field of 0.3 T at an angle of 30° to the field. What is the radius of the particle's path?

• A wire carrying a current of 8 A is wrapped around a soft iron core with a permeability of 200. If the coil has 20 turns and a radius of 0.2 m, what is the magnetic field inside the core?

• A wire carrying a current of 6 A is bent into a loop with a radius of 0.3 m. If the loop is placed in a magnetic field of 0.5 T, what is the torque on the loop if the field is perpendicular to the plane of the loop?

• A transformer has 2000 turns in the primary coil and 1000 turns in the secondary coil. If the current in the primary coil is 2 A, what is the current in the secondary coil?

• A solenoid with 100 turns has a length of 0.1 m and a radius of 0.01 m. If a current of 3 A flows through the solenoid, what is the magnetic field at the center of the solenoid?

• A charged particle with a charge of 4 μC and a velocity of 4 m/s enters a magnetic field of 0.2 T at an angle of 45° to the field. What is the force on the particle?

These numerical problems cover a range of concepts related to magnetic effects, including magnetic field, magnetic force, magnetic flux, solenoids, transformers, and charged particle motion in magnetic fields.