The following diagram gives the formula for charge and current. Scroll down the page for more examples and solutions on how to use the formula.

In these lessons, we will

• Calculate the charge flow in a circuit.

• Describe what is meant by an electric current.

• Calculate charge from current or current from charge.

Electric charge is measured in Coulombs (C).

A current of 1 Ampere = 1 Coulomb of charge flowing per second.

The size of the electric current is the rate of flow of the electrical charge.

Q = I × t

Examples:

1. Given that the current is 0.3A, calculate the charge flowing in the circuit in 20 seconds.

2. 360 C of charge flows around a circuit in 400 s. Calculate the current in the circuit.

Examples:

1. A current of 2A flows through a bulb for three minutes. Calculate the amount of charge that flows through the bulb in this time.

2. A charge of 5kC flows through a variable resistor in two minutes. Calculate the reading on the anmeter which is connected to the circuit.

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