Week 6

Question 1

Magnetic flux definition

Answer 1

Scalar product between the magnetic flux density with vector of area

Question 2

Vector of Area is always perpendicular to?

Answer 2

The surface area A

Question 3

Magnetic flux scalar or vector

Answer 3

Scalar

Question 4

Units of magnetic flux

Answer 4

Wb Weber
T m^2 Tesla meter squared

Question 5

Definition of electromagnetic induction

Answer 5

Prouction of an induced e.m.f (or voltage) across a conductor or circuit situated in a changing magnetic field

Question 6

Meaning of changing in magnetic flux

Answer 6

Change in number of magnetic field lines ‘cut’ by applying a relative motion.

Question 7

Who created Faraday’s law

Answer 7

Michael Faraday

Question 8

Magnitude of induced emf can be increased by increasing the

Answer 8

Speed of relative motion v
Number of turns N
Strength of magnet B
Area of coil or solenoid A

Question 9

What is Faraday’s Law of induction

Answer 9

The magnitude of the induced emf is proportional to the rate of change of the magnetic flux

Question 10

Direction of induced emf can be determined by

Answer 10

Fleming right hand rule (Thumb V Pointer B Middle induced emf)

Question 11

What is Lenz’s law

Answer 11

An induced current always flow in a directon that opposes the change in magnetic flux hat causes it

Question 12

Using Lenz’s law describe what happens when magnet move towards solenoid

Answer 12

When magnet move towards solenoid, North pole will be induced on the side of solenoid facing the magnet’s north pole.

This will cause the magnet to repel opposing the movement of the magnet which is moving towards the coil (opposing the change in magnetic flux that causes the induced current)

Question 13

Using Lenz’s law describe what happens when magnet move away from solenoid

Answer 13

When magnet move away from solenoid, South pole will be induced on the side of solenoid facing the magnet’s north pole.

This will cause the magnet to attract opposing the movement of the magnet which is moving away from the coil (opposing the change in magnetic flux that causes the induced current)

Question 14

Why is Lenz’s law an example of principle of conservation of energy

Answer 14

Mechanical work is done to against the opposing magnetic force experienced by the moving magnet, and this work is converted into electrical energy as indicated by induced flowing in the circuit.

Question 15

Faraday’s law gives waht

Answer 15

Magnitude of induced emf

Question 16

Lenz’s law gives what

Answer 16

Direction of induced emf