Physics Concepts: Motors and Transformers

Front

What happens to the rotation of the coil when using a battery with a larger potential difference?

Back

The rotation increases.

Front

What happens when using a stronger magnetic field?

Back

The rotation increases.

Front

How does a voltage across the primary coil cause a voltage across the secondary coil in a transformer?

Back

The changing magnetic field induces a voltage in the secondary coil.

Front

What design feature causes the voltage across the secondary coil to be larger than the primary coil?

Back

More turns in the secondary coil than in the primary coil.

Front

Calculate the current in the secondary coil if the primary input is 24,000V, 12,000A and the output is 400,000V.

Back

Current in secondary coil = (Primary Voltage x Primary Current) / Secondary Voltage.

Front

Why is it cheaper to transmit electrical energy at high voltage?

Back

1. Reduces energy loss due to resistance. 2. Allows for thinner cables used.

Front

Why does the needle of a voltmeter deflect when a magnet is inserted into a solenoid?

Back

The changing magnetic field induces an electromotive force (emf).

Front

What is the effect of inserting the magnet more slowly into the solenoid?

Back

The needle deflects less.

Front

What is observed when the magnet is withdrawn from the solenoid?

Back

The needle deflects in the opposite direction.

Front

Describe the operation of a transformer connected to an alternating voltage.

Back

The alternating current in the primary coil creates a changing magnetic field, which is then strengthened and channeled by the iron core to the secondary coil, inducing a voltage (emf) in the secondary coil.