paper 2 equations :(

Question 1

power in transformers

Answer 1

voltage in primary coil x current primary coil = voltage in secondary coil x current secondary coil

Question 2

p.d : turns transformer

Answer 2

p.d primary coil / p.d secondary coil = turns primary coil / turns secondary coil

Question 3

efficiency

Answer 3

efficiency = useful energy output / total energy input

Question 4

work done =

Answer 4

work done (J) = force (N) x distance moved (m)

Question 5

change in gravitational potential energy =

Answer 5

change in GPE (J) = gravitational field strength (N/kg) x mass (kg) x change in vertical height (m)

Question 6

kinetic energy =

Answer 6

kinetic energy (J) = 1/2 x mass (kg) x velocity^2 (m/s)

Question 7

power, work done or energy, time relationship

Answer 7

power (W) = work done OR energy transferred (J) / time (s)

Question 8

density =

Answer 8

density (g/cm^3 or kg/m^3) = mass (g or kg) / volume (cm^3 or m^3)

Question 9

charge, current, time relationship

Answer 9

charge (C) = current (A) x time (s)

Question 10

energy transferred, p.d, charge relationship

+ breakdown

Answer 10

energy transferred (J) = charge (C) x voltage/p.d (V)

energy transferred (J) = current (A) x time (s) x voltage/p.d (V)

Question 11

p.d, current, resistance relationship

Answer 11

potential difference (V) = current (A) x resistance (Ω)

Question 12

power, current, p.d relationship

Answer 12

power (W) = current (A) x p.d (V)

Question 13

power, current, resistance relationship

+ explanation to self

Answer 13

power (W) = current^2 (A) x resistance (Ω)

because normal power = current x p.d
and p.d is current x resistance
SO
this becomes current x current x resistance

Question 14

size of force (motor effect)

Answer 14

force (N) = magnetic flux density ( T or N/Am) x current (A) x length (m)