Questions Corrections 2018 Flashcards
(10 cards)
Explain why friction causes the student to become negatively charged
Transfer of electrons
From the carpet to the student
The negatively charged student touches a metal tap and receives an electric shock
Explain why
There is a potential difference between the student and the tap
Which causes electrons to transfer from the student
Which earths the charge
Some carpets have thin copper wires running through them why does this make a student less likely to receive an electric shock
Copper has a low resistance
So lower build up of charge
Explain how the resistance of a filament lamps changes as the potential difference across it increases
Current increases when potential difference increases
Which causes the temperature of the filament to increase
So the resistance increases
Energy efficient meaning
Higher useful energy output for the same total energy input
Explain the ideal properties of a radioactive source for use in medical diagnosis
Short half life so less damage to cellsh
Low ionising power so less damage to cells
Highly penetrating so it can be detected outside the body
So emits gamma radiation is ideal.
Explain how the temperature increases would affect the pressure exerted by the gas
Increase the pressure in the tube so higher kinetic energy of particles
The internal energy of the air increases as the tyre is inflated, explain why
Work is done on the air
So the temperature increases
Advantages of nuclear power
No carbon dioxide emitted
Doesn’t doesn’t cause global warming
More energy released per kg of fuel
The power output of the turbine is directly proportional to the kinetic energy of the air passing the blades each second.
Describe the effect on the power output when the wind speed is halved
Mass of air passing the turbine blades is halved which decreases kinetic energy by a factor of two
Decreasing kinetic energy by a factor of four
So kinetic energy decreases by a factor of 8
