The lamp with no filament

The idea

A Light Emitting Diode (LED) has no filament; it has two terminals, a positive one attached to the longer wire and a negative one attached to the shorter wire.

A new kind of lamp

Many torches today do not use the old kind of lamp. They use an LED lamp. LED stands for Light Emitting Diode.

Do you think an LED has a filament like the old lamp?

• Yes, a thin glowing wire
• No, it has no filament
• Yes, but it is hidden

Old lamp, new lamp

Look at the old lamp and the LED side by side. Follow the prompts.

Long is positive

A Light Emitting Diode (LED) has no filament. It has two terminals: a positive one attached to the longer wire and a negative one attached to the shorter wire.

A torch may use one or more LEDs, sometimes of different shapes.

• Incandescent lamp | LED
• Filament | yes | no
• Terminals | metal case and metal tip | 2: longer wire and shorter wire
• Positive terminal | not marked | longer wire
• Negative terminal | not marked | shorter wire

Notes

An LED has no filament. Its longer wire is the positive terminal and its shorter wire is the negative terminal.

Check yourself

Which lamp has no filament?

The positive terminal of an LED is attached to the _ wire.

How many terminals does an LED have?

Answer: 2

An LED has two terminals: the longer wire (+) and the shorter wire (–).

LED stands for...

• Incandescent lamp. It has a filament that glows.
• LED — correct. Yes! An LED has no filament.
• Both. Only one of them has no filament.
• longer — correct. Yes! Longer wire, positive terminal.
• shorter. The shorter wire is the negative one.
• thicker. It is the length that tells them apart, not the thickness.
• Light Emitting Diode — correct. Yes! A diode that emits light.
• Long Electric Device. That is not what the letters mean.
• Low Energy Dot. That is not what the letters mean.