P4-P5 Electricty Equations

Question 1

Equation of charge flow in a circuit

Answer 1

Charge (Coulombs) = Current (Amps) x Time Taken (Seconds)

Question 2

Equation for potential difference across a component

Answer 2

PD across a component (Volts) = Energy Transferred (Joules) / Charge (Coulombs)

Question 3

Equation for resistance across an electrical component

Answer 3

Resistance (Ohms) = PD (Volts) / Current (Amps)

Question 4

Equation for the resistance of an appliance

Answer 4

Resistance (Ohms) =PD (Volts) x Current (Amps)

Question 5

Total resistance of two components in series

Answer 5

Total Resistance (R) = R1 + R2

Question 6

Equation of the current passing through each component

Answer 6

Current (Amps) = Potential Difference (Volts) / Component Resistance (Ohms)

Question 7

Equation of Power of an appliance

Answer 7

Power (Watts) = Energy Transferred (Joules) / Time (Seconds)

Question 8

Calculating Power in an appliance per second

Answer 8

Power Supplied (Watts) = Current (Amps) x Potential Difference (Volts)

Question 9

Equation for power supplied to a resistor

Answer 9

Power (Watts) = Current2 (Amps) x Resistance (Ohms)

Question 10

Equation for energy transferred to a mains appliance in a given time

Answer 10

Energy Transferred to the mains (Joules) = Power (Watts) x Time (Seconds)

Question 11

Equation for power supplied to an electrical appliance

Answer 11

Power (Watts) = Current (Amps) x PD (Volts)

Question 12

Efficiency equation for power supply in a device

Answer 12

Efficiency = (its output power/its input power) x 100