Charge & Current (OCR GCSE Physics A (Gateway Science Suite)): Revision Notes
2.1.2 Charge & Current
Circuit Components
Circuits can consist of a variety of circuit components. Each component has its own properties and functions.
In a circuit diagram, specific symbols, known as circuit symbols, are used to represent these components.
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 (C) and current is measured in amperes (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 (s) using the following equation:
Formula
- = charge flow in coulombs (C)
- = current in amps (A)
- = time in seconds (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 minute and then opens it again. During this minute, the ammeter reads 2.5 A.
Calculate the charge that flowed through the circuit during the time that the switch was closed.
[3 marks]