Electromagnetic Induction

Question 1

What can we do to increase the size of the induced p.d (& current) when moving a wire in a magnetic field?

Answer 1

-move the wire faster
-use stronger magnets (increases magnetic flux density)
-increase the length of the wire which is in the magnetic field

Question 2

What can we do to reverse the direction of the induced p.d (& current) when moving a wire in a magnetic field?

Answer 2

-reverse the direction in which the wire is moved
-reverse the magnetic field direction

Question 3

What happens when moving a wire in a magnetic field?

Answer 3

1) If we move the wire downwards, the voltmeter reading changes from 0 to above 0 as a p.d has been induced across the wire
2) Reversing the direction in which the wire is moved, reverses the direction of the infused p.d reading from the voltmeter (& current if circuit is complete)

Question 4

What can we do to increase the size of the induced p.d (& current) when moving a magnet near a coil of wire?

Answer 4

-move the magnet faster
-use a stronger magnet (increases magnetic flux density)
-increase the number of turns in the coil
-increase the area of the coil

Question 5

What can we do to reverse the direction of the induced p.d (& current) when moving a magnet near a coil of wire?

Answer 5

-reverse the direction in which the magnet is moved
-reverse the magnetic field direction (by rotating the magnet 180° so the other pole is closer to the coil)

Question 6

What happens when moving a magnet near a coil of wire?

Answer 6

1) When the magnet is moved closer to the coil, a p.d is induced across the coil and as it’s connected to a circuit, a current flows through it
2) This is because part of the coil next to the N pole of the magnet becomes an induced N pole, resulting in a repulsive force between them
3) Work must be done against this repulsive force force in order to push the magnet towards the coil
4) This work is an input of energy into the system which is transferred to the electrical energy store of the moving charges which make up the induced current

Question 7

How can a magnetic field be generated?

Answer 7

When an induced current flows through a wire

Question 8

How can a p.d be induced in a wire?

Answer 8

When the wire is moved through a magnetic field or when a permanent magnet is moved close to it as whenever the magnetic flux through a conductor changes, a p.d is induced across it