Electricity And Magnetism

Question 1

Explain:
Induced magnetism

Answer 1

is when a material becomes like a magnet because it’s near another magnet. This happens in some materials when they’re near magnets, and it’s important in things like making electromagnets and storing information on computer hard drives.

Question 2

Explain:
Electric Field Patterns -

Answer 2

(a) Around a point charge, the electric field forms radial lines that extend outward in all directions. The direction of the electric field points away from the positive charge and towards the negative charge.
(b) Around a charged conducting sphere, the electric field is also radial, but it’s stronger near the surface of the sphere. The direction of the electric field at any point outside the sphere points away from the center of the sphere and behaves as if all the charge is concentrated at the center.
(c) Between two oppositely charged parallel conducting plates, the electric field forms uniform, parallel lines that are perpendicular to the plates. The direction of the electric field points from the positive plate to the negative plate. This creates a uniform electric field between the plates.

Question 3

What is Fleming’s Right-Hand Rule:

Answer 3

• Used to determine the direction of the force experienced by a current-carrying conductor in a magnetic field.
• Thumb: Points in the direction of the current (I).
• Forefinger: Points in the direction of the magnetic field (Bearing).
• Middle finger: Points in the direction of the force experienced by the conductor (F).

Question 4

Explain:
Direct Current (DC):

Answer 4

• DC flows in one direction only, with a constant polarity.
• It is typically produced by batteries, solar cells, or rectifiers.
• In a circuit, the voltage remains constant over time.
• DC is commonly used in electronics, such as in portable devices like cell phones and laptops, as well as in automotive systems.

Question 5

Explain:
Alternating Current (AC):

Answer 5

• AC periodically reverses direction, changing polarity over time.
• It is generated by power stations and distributed through power grids.
• In a circuit, the voltage and current alternate in a wave like form.
• AC is preferred for long-distance power transmission because it can be easily converted to different voltage levels using transformers.
• Most household appliances, industrial machinery, and electrical grids operate on AC.

Question 6

What is Fleming’s Left-Hand Rule

Answer 6

• Used to determine the direction of the current induced in a conductor moving through a magnetic field (also known as the generator rule).
• Thumb: Points in the direction of motion (V) of the conductor.
• Forefinger: Points in the direction of the magnetic field (Bearing).
• Middle finger: Points in the direction of the induced current (I).

Question 7

Construction of a Simple Transformer with a Soft Iron Core:

Answer 7

1. The transformer consists of two coils of wire, known as the primary coil and the secondary coil, wound around a soft iron core.
2. The primary coil is connected to an alternating current (AC) power source, while the secondary coil is connected to the load.
3. The soft iron core provides a path for the magnetic flux generated by the alternating current in the primary coil to link with the secondary coil.

Question 8

Principle of Operation

Answer 8

1. When alternating current flows through the primary coil, it creates a changing magnetic field around the coil.
2. This changing magnetic field induces an alternating voltage in the secondary coil through electromagnetic induction.
3. The induced voltage in the secondary coil depends on the ratio of the number of turns in the primary coil to the number of turns in the secondary coil (N1/N2) according to Faraday’s law of electromagnetic induction.
4. As a result, the transformer can step up or step down the voltage depending on the turns ratio and is capable of transferring electrical power from one circuit to another without a direct electrical connection.

Question 9

Use of Transformers in High-Voltage Transmission:

Answer 9

1. Transformers are essential in high-voltage transmission systems to reduce energy losses and increase efficiency.
2. High-voltage transmission lines use step-up transformers to increase the voltage for efficient long-distance transmission.
3. At the receiving end, step-down transformers reduce the voltage to safer levels for distribution to consumers.

Question 10

Advantages of High-Voltage Transmission:

Answer 10

1. Reduced Energy Losses: Transmitting electricity at high voltages reduces energy losses due to lower current levels, as power loss is proportional to the square of the current according to Joule’s law.
2. Increased Efficiency: Higher voltages allow for efficient long-distance transmission of electricity, enabling power generated at remote locations to reach consumers with minimal loss.
3. Cost Savings: High-voltage transmission systems require fewer conductors and smaller cross-sectional areas, resulting in lower material costs and reduced infrastructure investment.