Physics Test - Electricity

Charge and Current

• when there is a complete closed circuit, an electric current will flow

Current-rate of flow of charge (how fast the charge flows)

• current is measured in amperes (A) using an ammeter
• the electrons in the circuit are attracted to the positive terminal of the battery.  However, conventional current flows from positive to negative

Types of circuits

• in parallel circuits, components are connected across each other
• in series circuits, components are next to each other
• the unit of electric charge is coulomb (C)

Electric current = electric charge / time

A=C/s

Voltage

• a voltmeter measures the amount of energy transferred in a component
• the voltage(potential difference) is measure in volts

Potential difference = energy / charge

v=J/C

Try this  out:

A cell has a potential difference of 1.5 V.

What is meant by the term 'potential difference'

Calculating power

• Electrical power is the rate of energy transfer. 
• It's measured in watts (W)

power = energy transferred / time

W=J/s or P=E/t

Kilowatt-hours

The energy used by an appliance can be calculated: energy=power x time (J=Wxs)

1 kilowatt-hour is the nergy used by a 1 kW appliance in 1 hour.

energy (kWh) = power (kW) x time (h)

Cost of electricity is calculated using the equation below:

cost (p) = power (kW) x time (h) x cost per kWh (p/kWh)

 Fossil fuels and nuclear fuel are non-renewable resources because they cannot be replaced and will eventually run out.

Renewable energy sources