Electrodynamics

Question 1

Where does a magnetic field exist?

Answer 1

Around a permanent magnet.
OR
Around a current-carrying conductor.

Question 2

What happens to a current carrying-conductor when placed in a magnetic field?

Answer 2

A force might act on the current-carrying conductor.

Question 3

What do motors do in relation to energy?

Answer 3

Motors convert electrical energy to mechanical energy.

Question 4

What is magnetic flux density (B) ?

Answer 4

Magnetic flux density (B) is a representation of the magnitude and direction of the magnetic field.

Question 5

Magnetic Flux Linkage

Answer 5

The product of the number of turns on the coil and the flux through the coil (NØ).

Question 6

Faraday’s Law of electromagnetic induction

Answer 6

The emf induced is directly proportional to the rate of change of magnetic flux (flux linkage).

Question 7

Lenz’s Law

Answer 7

The induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux.

Question 8

What do generators do in relation to energy?

Answer 8

Generators convert mechanical energy to electrical energy.

Question 9

What is the difference between motors and generators?

Answer 9

Generators convert mechanical energy to electrical energy.
Motors convert electrical energy to mechanical energy.

Question 10

What are the factors that affect the emf induced? Provide reasons for your answers.

Answer 10

• Rate of change of magnetic flux: Greater change induces more emf.
• Number of turns in the coil: More turns induce more emf.
• Strength of the magnetic field: Stronger fields induce more emf.
• Area of the loop: Larger areas induce more emf.
• Angle between the magnetic field and coil: Optimal angle (θ = 0∘) induces maximum emf.
• Velocity of relative motion: Faster motion induces more emf.

Question 11

Where will you find a slip ring?

Answer 11

In an AC generator.

Question 12

What is a slip ring?

Answer 12

A slip ring is an electromechanical device that allows the transmission of electrical signals and power from a stationary structure to a rotating one.

Question 13

What are the characteristics of an ideal transformer in relation to power?

Answer 13

Input power is equal to output power.

Question 14

Diode

Answer 14

A component that only allows current to flow in one direction.

Question 15

How is a single diode is used for the half-wave rectification of an alternating current?

Answer 15

Asingle diode allows current to pass only during the positive half of the AC cycle, blocking it during the negative half. This process converts the AC signal into a pulsating DC signal, achieving half-wave rectification.

Question 16

What is the difference between half-wave and full-wave rectification graphically?

Answer 16

Half-Wave Rectification: The graph of the output voltage shows only the positive half of the AC sine wave, with the negative half missing.
Full-Wave Rectification: The graph of the output voltage shows both halves of the AC sine wave, but the negative half is inverted, resulting in a series of positive pulses with no gaps.