Electric circuits--How does a switch work?

By Admin on

Electric circuits

1a. Basic circuits: a lamp and a cell

Simple circuit

Here is a simple electric circuit. It has a cell, a lamp and a switch. To make a circuit, these components are connected together with metal connecting wires.

When the switch is closed, the lamp lights up. This is because there is a continuous path of metal for the electric current to flow around. If there were any breaks in the circuit, the current could not flow.

The current flows all the way around the circuit. The cell pushes the current around the circuit. As the current passes through the lamp, it makes it light up.

Components in a circuit - interactive graphic

Series circuit

This circuit is called a series circuit. The components are connected end-to-end, one after the other. They make a simple loop for the current to flow round

How does a switch work?

A simple switch is made of a metal lever that can join up with a metal contact. When you press the switch, the two pieces of metal touch and the current can flow through it. When you open it, this breaks the circuit.


Challenge 1
Make a simple series circuit with a cell, a lamp and a switch so that the lamp comes on when you close the switch.
This is like a torch circuit.
Challenge 2
What effect does the number of cells have? Adding cells to a battery and making the lamp brighter.
Challenge 3
Measure current in a simple series circuit. Find out if it gets used up.
Challenge 4
Find out what happens to the current if you change the number of cells in a battery.
Challenge 5
What effect does the number of lamps (in series) have? Try adding lamps in series and see what happens to the brightness.
Challenge 6
Try measuring the current in a series circuit with two lamps. How does it compare with the current in a circuit with a single lamp?
Challenge 7
Make a parallel circuit with a cell and two lamps. Try disconnecting one of the lamps. What happens to the brightness of the other one?
Challenge 8
What is the current at various points in a parallel circuit?
Challenge 9
Build some challenging circuits.
Challenge 10
Build some more challenging circuits with 4 cells.


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