Electromagnetic induction

Question 1

Magnetic flux linkage

Answer 1

The product of the number of turns on the coil and the flux through the coil (*+)

Question 2

Faraday’s law of electromagnetic induction:

Answer 2

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

Question 3

Lenz’s law:

Answer 3

the induced current flows in a direction so as to set up

a magnetic field to oppose the change in magnetic flux

Question 4

State that for an ideal transformer, ____ power is equal to ____ power.

Answer 4

State that for an ideal transformer, input power is equal to output power

Question 5

Diode

Answer 5

A component that only allows current to flow in one

direction

Question 6

Factors affecting emf : (4)

Answer 6

• The greater the speed of the movement, the greater the emf induced
• Emf was zero when there was no motion
• The greater the area of the coil, the greater the emf
• The greater the number of coils, the greater the emf
• The greater the strength of the magnet, the greater the emf

Question 7

How do electric generators induce an emf?

Answer 7

Electric Generators induce an emf by rotating a coil in a magnetic field.

Question 8

How does a transformer work?

Answer 8

The secondary coil picks up this magnetic flux.
The secondary coil experiences a changing magnetic flux and so an emf is induced in the secondary coil. The iron core traps the magnetic field created by the primary core and its magnetization increases the field strength.

Question 9

The _____ _____ in a resistor is given by P=I^2R, so the smaller the current, the smaller the energy loss as electrical energy is transmitted through
the national grid.

Answer 9

power dissipated