The two ends of a cell

The idea

An electric cell is a portable source of electrical energy with two terminals: the metal cap is the positive (+ve) terminal and the metal disc is the negative (–ve) terminal.

A small helper

Torches, wall clocks, radios and TV remotes all hide the same small helper: an electric cell. It is a portable source of electrical energy, so the device works without a wall socket.

Look at the two ends of a cell. One end has a small metal knob (the cap). The other end is flat (the disc).

Which end do you think is the positive (+) one?

• The end with the knob (the cap)
• The flat end (the disc)
• Both ends are positive

Find the terminals

Find the two terminals of the cell. A wrong tap tells you what you touched.

Cap is plus

An electric cell is a portable source of electrical energy with two terminals: the metal cap is positive (+) and the metal disc is negative (–).

For experiments with electricity, use only cells or batteries, like those in torches, wall clocks, radios or remotes. Never experiment with the wall socket at home or school.

• Part of the cell | Terminal
• Metal cap (the knob) | positive (+)
• Metal disc (the flat end) | negative (–)

Notes

The metal cap is positive (+). The metal disc is negative (–). A cell is a portable source of electrical energy.

Check yourself

Which part of a cell is the positive (+) terminal?

A cell is a _ source of electrical energy.

How many terminals does an electric cell have?

Answer: 2

A cell has two terminals: the positive cap and the negative disc.

Which source is safe to use for experiments with electricity?

• The metal disc. The disc is the flat end. It is the negative terminal.
• The metal cap — correct. Yes! The knob at one end is the positive terminal.
• The label on the body. The body is not a terminal. Terminals are the two metal ends.
• portable — correct. Yes! You can carry it in a torch or a remote.
• fixed. A fixed source stays in one place. A cell can be carried around.
• wall-plugged. A cell works without a wall socket. That is why it is portable.
• A wall socket. Never do experiments with the power supply at home or school. It can be dangerous.
• A cell or battery, like in a torch — correct. Yes! Use only cells or batteries for experiments.
• A portable generator. Even electricity from a portable generator can be dangerous.