Circuit components

Syllabus statements

components

Unfortunately for you if you don't like physics, there are a number of electrical components you need to know about. Today I'll be going through them so hopefully you can understand their purposes better.

Click Read More to learn about components and their circuit symbols

Cells and batteries, switches and lamps

These are the simplest components you will need to know about.
First, cells and batteries. You probably know what batteries are, they're everywhere! But you may be surprised to know that they're made of several cells connected together.

The top symbol represents a single cell, with the longer line representing the positive terminal.

The bottom symbol represents a battery, the dotted line in between the 2 cells tells us there are more than 2 cells in this battery.

On to switches and lamps. They're pretty easy too.

Lamps are just light bulbs. Simple. Done. Now all you need to do is remember the easy circuit symbol for it.

Switches, simple. They're either on or their off.

On the right hand side we have a switch that is on and on the left hand side the switch is off.

Resistors

Resistors are a bit annoying because the Americans have their own symbol for them that isn't the international standard so when people search up resistors they get the wrong one. So let me set the record straight.

Whenever you're revising online and you see a circuit with a zig-zag line component, know that this is just a resistor!

There are 4 different types of resistors you need to know about. The first one is a fixed resistor, meaning the resistance of the resistor can't be changed. My previous post explains the affect of resistors on the current.

Learn about Voltage, Current and resistance!

The next type of resistor is a variable resistor. This is a resistor that does not have a fixed resistance value and you can change the value yourself. Variable resistors are also sometimes called rheostats (blame America).

The next 2 resistors are similar so I'll explain them together. LDRs and Thermistors resistance values are derived from their surroundings, they are basically sensors. LDR stands for Light Dependent Resistor and it's resistance changes when the light intensity changes. Thermistor as you may have guessed from words like thermal and thermostat changes its resistance when the temperature changes. The way they do this is the important thing to learn. It's easiest to explain these separately.
LDRs resistance increases as the light intensity decreases. So as it gets darker the resistance increases.
Thermistors do the same, as the temperature decreases the resistance increases.
if you draw this on a graph you will see resistance is inversely proportional temperature (or light intensity)

Diodes

Diodes are easy, they are basically just valves for current. You may remember valves from the heart in biology, they're basically the same. They only let current (like blood in the heart) flow in one direction.

Diodes naturally give out light when they're put into a circuit (no I'm not explaining) but this amount is so little that you don't see it in a normal diode. This is where LEDs come from. LED stands for Light Emitting Diode.

This is the symbol for an LED. You have probably heard of LEDs before, they are the new generation of lighting, much more efficient than the old filament bulb which uses 95% of the energy given to it to create useless heat.

Last of all, Ammeters and voltmeters

Ammeters measure current and voltmeters measure voltage. They both have different symbols and needed to be connected in different ways.

This is the symbol for an ammeter. Ammeters need to be connected in series as they are measuring the flow of current around the circuit.

This is the symbol for a voltmeter. Voltmeters need to be connected in parallel to the component/s you are measuring the voltage of because the voltage is a difference in energy between 2 points so it needs to be connected before and after.

Once again I hope this has been useful and if it hasn't please let me know in the comments so I can improve! If you have any questions or post requests drop me an email

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