Symbols and Units
The unit for current
Ampere (A)
A lightbulb is supplied with 500 J of energy. If it puts out 20 J of energy, what is its efficiency?
4%
The unit for voltage
R = 12 Ω
I = 0.5 A
V =?
6V
The unit for resistance
Ohms (Ω)
A circuit contains a 1.5 volt battery and a bulb with a resistance of 3 ohms. Calculate the current.
0.5A
The rate at which electrons flow past a certain point in the circuit
Current
A fridge uses 300kwh of electricity in a year. If the cost of electricity is 5¢/kwh, calculate the yearly cost of operating the fridge. Write your answer in dollars.
$16.50
Another name for potential difference
voltage
A 40 W night light is left on for 8 hours for 7 nights. Electricity costs 6¢/kWh. Calculate the weekly cost in cents.
13.44 cents