# Electrical Charge and Current

## Electrical Charge and Current Revision

**Electrical Charge and Current**

**Electric current** flows around circuits to power **circuit components** such as lamps, motors and buzzers.

**Circuit Components**

Circuits can be made up of a combination of many different **circuit components**. Different circuit components have different **properties** and **functions**.

In a **circuit diagram**, we use specific symbols called **circuit symbols** to represent each component.

You need to be able to draw and recognise the following **circuit symbols**.

**Electrical Current**

Electric current is a** flow of electrical charge**. Electrical charge is measured in **Coulombs** \text{(C)} and current is measured in **a****mperes **\text{(A)}. The current can be thought of as the **rate of flow** of charge around the circuit. You can measure current using an **ammeter**. You can calculate the charge that has flown around a circuit in a certain time \text{(s)} using the following equation:

\color{f21cc2}{Q=It}

- Q= charge flow in joules \text{(J)}
- I= current in amps \text{(A)}
- t= time in seconds \text{(s)}

Remember that current will only flow through a circuit when it makes a **complete loop**.

**Example: Calculating Charge**

A student connects a battery to an ammeter and a resistor as shown in the diagram. The student closes the switch for 1\text{ minute} and then opens it again. During this minute, the ammeter reads 2.5\text{ A}.

Calculate the charge that flowed through the circuit during the time that the switch was closed.

**[3 marks]**** **

## Electrical Charge and Current Example Questions

**Question 1:** Draw the circuit symbol for a LED.

**[1 mark]**

**Question 2:** Identify the following circuit component.

**[1 mark]**

**Variable resistor**.

**Question 3:** Define electrical current.

**[1 mark]**

The **flow** of **electrical charge**.

**Question 4**: How much charge flows past a bulb in 10\text{ s} in a circuit with a current of 4\text{ A}?

**[2 marks]**

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