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 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

80 km               -90°C                                                                                     d3 = 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.

          

MAGNETISM : Concept, Equation, Laws, FAQs & Numerical

MAGNETISM : Concept, Equation, Laws, FAQs & Numerical

Magnetism is a fundamental force of nature that is responsible for the attraction and repulsion between objects. It is the force that causes magnets to attract iron, nickel, and cobalt. The study of magnetism involves understanding the properties of magnets and their behavior, as well as the effects of magnetic fields on matter.

Concept:

Magnetism is the property of certain materials that enables them to attract iron, nickel, cobalt, or other magnetic substances. Magnets are materials that exhibit strong magnetic properties and can be used to create magnetic fields. The magnetic field is a region in space around a magnet where the force of magnetism can be detected.

The origin of magnetism lies in the motion of electric charges. When electric charges move, they create a magnetic field. This can be seen in the behavior of electrons, which are negatively charged particles that orbit the nucleus of an atom. The motion of electrons creates a magnetic field that can be detected outside the atom.

Equation:

The strength of a magnetic field is measured in units of tesla (T) or gauss (G). The magnetic field is a vector quantity, which means it has both magnitude and direction. The magnetic field is represented by the symbol B, and its magnitude is given by the equation:

B = F / (q * v * sinθ)

Where F is the force on a charged particle moving through the magnetic field, q is the charge of the particle, v is the velocity of the particle, and θ is the angle between the direction of the magnetic field and the direction of motion of the particle.

Laws:

There are several laws of magnetism that govern the behavior of magnets and magnetic fields.

• Law of Magnetic Poles: Every magnet has two poles, north and south, and opposite poles attract while like poles repel.

• Law of Magnetic Fields: The strength of the magnetic field decreases with distance from the magnet.

• Law of Magnetic Induction: A moving magnetic field can induce an electric current in a conductor.

• Ampere's Law: The magnetic field created by a current-carrying wire is proportional to the current and the distance from the wire.

FAQs:

• What is magnetism?

Magnetism is the property of certain materials that enables them to attract iron, nickel, cobalt, or other magnetic substances.

• What is a magnetic field?

A magnetic field is a region in space around a magnet where the force of magnetism can be detected.

• How do magnets work?

Magnets work by creating a magnetic field that interacts with other magnetic materials.

• What are the different types of magnets?

The different types of magnets include permanent magnets, electromagnets, and ferromagnets.

• What is the strength of a magnetic field measured in?

The strength of a magnetic field is measured in units of tesla (T) or gauss (G).

Numericals:

• A wire carries a current of 2.5 A. What is the magnetic field at a distance of 4 cm from the wire?

Solution:

Using Ampere's Law, we can calculate the magnetic field as:

B = (μ₀ * I) / (2 * π * r)

Where μ₀ is the permeability of free space, I is the current, and r is the distance from the wire.

Substituting the values, we get:

B = (4π * 10^-7 * 2.5) / (2 * π * 0.04)

B = 3.94 * 10^-5 T

• What is the magnetic force on a charge of 5 μC moving with a velocity of 100 m/s in a magnetic field of 0.5 T at an angle of 30 degrees to the direction of the magnetic field?

Solution:

Using the equation for the magnetic force on a charged particle, we can calculate the force as:

F = q * v * B * sinθ

Where q is the charge of the particle, v is its velocity, B is the magnetic field strength, and θ is the angle between the direction of the magnetic field and the velocity of the particle.

Substituting the values, we get:

F = (5 * 10^-6) * (100) * (0.5) * sin(30)

F = 1.25 * 10^-3 N

Conclusion:

Magnetism is a fascinating and complex phenomenon that is essential to many fields of science and technology. Understanding the principles of magnetism is essential for applications such as electric motors, generators, and magnetic resonance imaging (MRI). The laws of magnetism govern the behavior of magnets and magnetic fields, and the equations for magnetic force and field strength allow us to make quantitative predictions about their behavior.