Diodes and LEDs

Question 1

What is a diode?

Answer 1

• is an electronic device that is used to control the flow of current in an electrical circuit
• it allows the current to flow in one direction only
• it is a control device

Question 2

In which two ways are diodes used?

Answer 2

• 1) as rectifiers

- 2) as lights

Question 3

Explain how a diode is used as a rectifier?

Answer 3

• they allow electricity in a circuit to flow in one direction only
• like a one-way street or a turnstile at a stadium

Question 4

Explain how a diode is used as a light?

Answer 4

• some diodes emit light
• these are called light-emitting diodes or LEDs
• they are often used to indicate that a circuit is on or on standby
• more powerful LED’s are used in torches and small spotlights

Question 5

Are diodes polar or non-polar?

Answer 5

polar

Question 6

What does it mean if we say a diode is polar?

Answer 6

• it must be inserted the correct way in a circuit

- with the negative pole of the diode to the negative pole of the battery

Question 7

How is the negative pole of the diode identified?

Answer 7

• 1) Ordinary diodes are marked with a painted ring at the end of the negative end
• 2) LED’s have two legs. The shorter leg is the negative leg
• 3) The casing of the LED’s negative end is flat and the positive end is rounded