Transformers

Question 1

If an electrical conductor cuts through a magnetic field, a potential difference is induced across…

Answer 1

The ends of the coil

Question 2

If a magnet is moved into a coil of wire, a potential difference is induced across…

Answer 2

The ends of the coil

Question 3

What does an alternating current in the primary coil produce (in a transformer)? What does this induce across the ends of the secondary coil?

Answer 3

A changing magnetic field in the iron core and hence the secondary coil, inducing an alternating potential difference

Question 4

In a step-up transformer, the potential difference across the secondary coil is ____ than the potential difference across the primary coil

Answer 4

Greater

Question 5

In a step-down transformer, the potential difference across the secondary coil is ___ the potential difference across the primary coil

Answer 5

Less

Question 6

What do switch mode transformers operate at a high frequency between?

Answer 6

50 kHz and 200 kHz

Question 7

What are switch mode transformers much lighter and smaller than?

Answer 7

Traditional transformers working from a 50 Hz mains supply

Question 8

What are switch mode transformers useful as? Why?

Answer 8

Mobile phone chargers, as they’re light

Question 9

Switch mode transformers use very little power when they are switched on, but…

Answer 9

No load is applied