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
Electrical circuits 2
- a voltmeter measures the amount of energy transferred in a component
- the voltage(potential difference) is measure in volts
Potential difference = energy / charge
Try this out:
A cell has a potential difference of 1.5 V.
What is meant by the term 'potential difference'
- 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
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.
Energy resources 2
Renewable energy sources