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Flashcards in Exam Questions Deck (9)
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1

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

Transfer of electrons
from the carpet to the student

2

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

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

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)

Carpet/copper has a low resistance
Lower/no build up of charge on student

4

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

power = work done/time

5

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

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

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)

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

7

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

Potential difference
Temperature

8

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

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

9

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

Alpha radiation is not very penetrating/ does not penetrate skin