power

Question 1

how do kettles transfer energy?

Answer 1

-electrically from the mains ac to the thermal energy store of the heating element inside the kettle

Question 2

how do fan’s transfer energy?

Answer 2

transferred electrically from the battery to the kinetic energy store of the fan’s motor

Question 3

what does the amount of energy an appliance transfers depend on?

Answer 3

how long the appliance is switched on for
the power of the appliance

Question 4

standard equation of power and energy transferred, give units

Answer 4

E=Pt
J, W, s
energy transferred = power x time

Question 5

what happens to the energy transferred if the power is higher?

Answer 5

it is higher

Question 6

power rating

Answer 6

the maximum amount of energy transferred between stores per second when the appliance is used

Question 7

energy transferred and charge, include units

Answer 7

E=QV
J, C, V
energy transferred=charge x potential difference

Question 8

what happens when an electrical charge goes through a change in pd?

Answer 8

energy is transferred

Question 9

describe the path of charge

Answer 9

-energy supplied to charge at the power source to raise it through a potential
-charge gives up this energy when it falls through any potential drop in components
-means that a battery with a bigger pd will supply more energy to the circuit for every coulomb of charge that flows round it as the charge is raised higher at the start

Question 10

power, pd and current, give units

Answer 10

P=VI
W, V, A
power=potential difference x current

Question 11

power, current and resistance, give units

Answer 11

P=I²R
W, A, ohms
power=current² x resistance