A bright heater and a dim phone charger both run on electricity, but one pours out energy far faster. Power is simply that rate, and it follows from current and voltage in a single step.
Electrical power is the rate of transferring energy, P = I multiplied by V, measured in watts. Over a time t the energy transferred is E = I multiplied by V multiplied by t.
Electrical power is the rate at which energy is transferred. The energy transferred is the power multiplied by the time.
Power is in watts (W), energy in joules (J), time in seconds. One watt is one joule per second.
Set the current and voltage and watch the power, then the energy build up over time.
Four quick checks. Each correct answer earns XP and lights this skill on your star map.
Electrical power is given by...
The unit of power is the...
The electrical energy transferred is...
One watt is the same as one...
Multiply power by time to get the energy transferred.
A heater takes a current of 5.0 A from a 240 V supply. Find its power.
Power is current multiplied by voltage, P = I V, in watts. To get the energy, multiply the power by the time, E = P t = I V t, in joules.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.
A heater takes 5.0 A from a 240 V supply. Its power is...
A 60 W lamp is switched on for 120 s. The energy it transfers is...
A 1500 W kettle runs from the 230 V mains. The current it draws is about...
Electrical power and energy are mapped. Keep the chain going.