Electrical charge and current

• Electrical current is the flow of electrical charge
• A bigger electric current means a faster flow of electrical charge.
• A smaller electric current means a slower flow of electrical charge.
• Electrical charge only flows when there are components in the circuit that can transfer energy electrically
• charge only flows if there is a source of potential difference in the circuit.
• If there is a break or gap in the circuit, charge will not flow.
• In a closed circuit that is a single loop, the current is the same everywhere in the circuit.

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• Charge (coulombs) = Current (Amps) x time (seconds)
• The unit of charge is coulombs (C).
• The unit of current is amperes or amps (A
• The unit of time is seconds (s).
• For example, if a current of 1.5 A passes through a bulb for 30 seconds, what is thecharge flow?.

  Plug the values into the equation:

  1.5 A × 30 s = 45 C.

  So the charge flow is 45 coulombs.
• Power = potential difference (V) x current (A)
• Energy transferred = power x time
• A component that is sensitive to light is a light dependent resistor (LDR).
• This circuit depends on temperature, so needs a thermistor to respond to changes in temperature.
• A fuse is made up of a thin wire designed to melt if too much current flows through it.
• This circuit depends on light intensity, so needs a light dependent resistor (LDR) which switches lights on automatically when it gets dark
• Current = charge / time
• Current is the rate of flow of electrical charge