Y11 PHY T1 H.W 10

Which kind of transformer is this?

• a step up transformer

• a step down transformer

• no step transformer

• none of the above

What is induced emf?

• Electromotive force generated in a conductor by a changing magnetic field.

• The potential difference between two points in a circuit

• The resistance in a circuit

• The force exerted by an electric current

What happens when a wire cuts through magnetic field lines?

• It breaks

• It becomes magnetic

• It generates heat

• A voltage is induced

What did Michael Faraday say about induced EMF?

• It is inversely proportional to the rate of change of magnetic flux

• It decreases with the increase of magnetic flux

• It is proportional to the rate of change of magnetic flux

• It is constant regardless of the magnetic flux

In Fleming's Right Hand Rule, First finger and center finger represent

• current, magnetic field

• magnetic field, current

• force, current

• magnetic field, force

Which of the following increases frequency of AC?

• increasing number of turns on the coil

• using a stronger magnet

• rotating the coil faster

• increase area of the coil

What would happen if I move a bar magnet in and out of a coil of copper wire?

• Electric current would disappear 
• The magnet would explode 
• Electric current will flow through the wire
• It would produce a gravitational field

The diagram shows a transformer.

The input voltage is 240 V.

What is the output voltage?

• 6 V

• 12 V

• 20 V

• 40 V

A magnet is suspended from a spring so that it can move freely inside a stationary coil. The coil is connected to a sensitive centre-zero galvanometer.

The magnet repeatedly moves slowly up and down.

What does the galvanometer show?

• a constantly changing reading

• a steady reading to the left

• a steady reading to the right

• a steady reading of zero

An e.m.f. is induced across a wire when it moves through the magnetic field between the poles of a magnet.

Which electrical device operates because of this effect?

• a battery

• a cathode-ray tube

• a generator

• a motor