2018 Paper 1 Flashcards
Explain why having copper wires under a carpet stops someone from receiving an electric shock when walking on that carpet
Copper is a good conductor of electricity so electrons flow through wire instead of student
How does cycling uphill affect maximum speed of cyclist
Maximum speed of cyclist will decrease. Total power output stays the same but WORK IS DONE AGAINST GRAVITY so maximum speed must decrease as height increases so gravitational potential energy increases.
What is current and potential difference like on a series circuit
Current - same everywhere which is why you can add total resistance and divide by potential difference
Potential difference - shared in proportion with resistance
Explain why beta and gamma wouldn’t work in a smoke alarm
Beta and gamma radiation will penetrate through smoke so change in count rate won’t be detected compared to alpha which has a low penetrating range so alpha radiation can be absorbed by smoke
What is meant by a random error
Measurements are incorrect by a different unpredictable amount each time
Why does internal energy increase when a tyre is inflated
Work is done on the air in the tyre so temperature of air increases as kinetic energy increases
Advantages of nuclear fusion
Doesn’t produce any co2 emissions so doesn’t contribute to global warming
If the power out of a blade is directly proportional to the kinetic energy of the air passing through it, explain what happens to power output when speed of air is halved
The mass of air passing through blade each time halves, so kinetic energy halves
The velocity of air is halved so kinetic energy decreases by a factor of 4 (2²)
So overall kinetic energy decreases by a factor of 8 so power output decreases by factor of 8
What happens to potential difference if resistance decreases
Potential difference increases as there is a bigger difference between current (as it decreases when resistance increases) and resistance
