PAPER 2

Question 1

What is the specific heat capacity

Answer 1

The amount of energy required to increase 1kg of a substance by 1 Celsius degrees per kilogram by mass

Question 2

How does a transformer work?

Answer 2

1) the AC current flows through the PRIMARY COIL, with the current direction changing continuously
2) this produces a changing magnetic field around the coil, which magnetises the iron core (a soft magnetic material)
3) the iron core then has an alternating magnetic field which is transferred to the secondary coil,
4) the alternating magnetic flux cuts across the secondary coil, inducing a voltage
5) the size of the voltage depends on how many turns are on the secondary coil compared to the primary coil
6) the voltage will increase, if there are more turns on the secondary coil: a step-up transformer
7) the voltage will decrease, if there are less turns on the secondary coil: a step-down transformer

Question 3

How are transformers used in large-scale transmissions

Answer 3

1) BEFORE transmission: step-up transformers used
2) INCREASE the voltage
3) DECREASE the current
4) reducing heating of the transmission cables
5) which minimizes energy loss to the surroundings/ improves efficiency of transmission/ less energy wasted

6) AFTER transmission: step-down transformers used
7) DECREASES voltage
8) INCREASES current
9)for SAFETY as electricity enters households

Question 4

The weight of a body acts through..

Answer 4

It’s centre of gravity