iGCSE Electricity Topic: Circuits and Diagrams

cell

battery

battery

resistor

variable resistors

thermistor

heater

potential divider

fuse

light dependent resistors

switch

diodes

voltmeter

oscilloscopes

lightbulb

motor

cell

These are individual stores of chemicals which are used to create an EMF, like the ones you’ve made in chemistry. The batteries you put in your TV remote are lots of cells joined together. The long side is positive and the short side is negative.

battery

If a battery is made of several cells together, then it makes sense for the symbol to be several cell symbols together. It can be drawn two ways.

resistors

A generic resistor that has no job other than to slow down the current by a set amount is depicted like a box

variable resistors

This is a resistor that we can change the resistance of These are used in dimmer switches, thermostats, etc…

thermistors

This is another type of variable resistor, but the amount of resistance is controlled by the temperature instead of a person.

heaters

Most resistors dissipate their energy by heat. An electric heater is actually just a really big resistor. It looks like a resistor with stripes.

light dependent resistors

This is another type of variable resistor, but the amount of resistance is controlled by the light shining on it instead of a person.

fuses

This is a resistor that is designed to break if there is too much current flowing through it.

potential dividers

This is resistor to which a third wire can be attached to allow some of the current to skip part of it, putting less resistance on that current. It looks like a resistor with a third wire pointing to it.

switches

This is exactly what it sounds like, it turns off or on the part of the circuit it is in by breaking or completing the circuit.

diodes

A diode only allows a current to flow through in one direction (the direction it is pointing). This can be useful to protect certain devices that only work if the current flows the right way, or for turning AC in to DC.

voltmeter

As the name suggests, these are used to measure the potential difference across a part of the circuit.

oscilloscopes

They are used to electronically graph the current or voltage flowing through them. They are usually used to measure an alternating current.