Exam Questions

Question 1

A student becomes negatively charged because of the friction between his socks and the carpet. Explain why (2)

Answer 1

Transfer of electrons

from the carpet to the student

Question 2

The negatively charged student touched a metal tap and receives an electric shock. Explain why (3)

Answer 2

There is a potential difference between student and tap
which causes electrons to transfer from the student to the tap
which earths the charge

Question 3

Some carpets have thin copper wires running through them. The student is less likely to receive an electric shock after walking on this type of carpet. Suggest why (2)

Answer 3

Carpet/copper has a low resistance

Lower/no build up of charge on student

Question 4

Write down the equation that links power. time and work done (1)

Answer 4

power = work done/time

Question 5

Calculate the work done by a cyclist when his power output it 200W for 1800 seconds (3)

Answer 5

200 = W/1800
W = 200 x 1800
W = 360,000 J

Question 6

The maximum speed a cyclist can travel on a level road is 14 m/s. How does cycling up hill affect the maximum speed of the cyclist? (3)

Answer 6

Maximum speed is lower
because maximum power output is constant
but additional work is done (against gravity)

Question 7

The current through an ohmic conductor is directly proportional to the _____ across the component, provided that the ______ remains constant (2)

Answer 7

Potential difference

Temperature

Question 8

Many households are replacing filament lamps with LEDs, which are more energy efficient. What does more energy efficient mean? (1)

Answer 8

A higher proportion/percentage of the total power/energy input is usefully transferred

Question 9

Why is it safe to use a source of alpha radiation in smoke alarms in a house?

Answer 9

Alpha radiation is not very penetrating/ does not penetrate skin