Science 4th grade | UNIT 5: Electricity and magnetism 5.1 Electricity flows in circuits
Activity 5.1 (Investigate a torch)
You will need: a torch with cells
If you turn on the torch what do you think will happen? Test your prediction.
What is inside the torch?
What do you think makes the light shine?
Safety: Be careful of cells. Do not open up any cell because the chemicals inside will burn you.
What is electricity?
The torch works because each cell pushes the electricity. This makes the bulb light up. Look at the picture of the inside of the torch.
Electricity can flow in one direction. We call this electrical current. You can think of current as particles travelling along a path. In the torch, the current flows from one end of the first cell to the other end. Then it flows through the next cell, through the bulb and back again into the first cell. Current needs a continuous path. This path is called a complete circuit.
What are cells?
A cell has a positive (+) and a negative - terminal. The current flows from the positive terminal to the negative terminal. If you use two cells, you must always put the negative terminal of one cell against the positive terminal of the other cell. Try this out with your torch.
Questions
1) What happens if you put the two positive terminals of the cells in a torch together? Will the bulb light up?
2) Explain why the cells in a torch have to be arranged with the negative terminal of one cell against the positive terminal of the other cell.