Albert Teen YOU ARE LEARNING:  Diodes and LEDs  # Diodes and LEDs ### Diodes and LEDs

This lesson looks at regular diodes and light-emitting diodes (LEDs) in a circuit diagram.

Which of the following are diodes? Pick all the options you think are correct. What does LED stand for? 1

Which of the diodes is this the circuit symbol for?  2

The function of a diode is to allow current to pass through it in only one direction.

The triangle in the symbol diagram for a diode is similar to the "give way" road sign - diodes only give current one way to flow. 3

The anode and cathode are defined by the flow of current. Current is the movement of negative electrons so the current flows from negative to positive.

So the triangle in the diode can be seen as an arrow pointing in the direction the current must flow through the diode. 1

What type of diode is this the circuit symbol for?  To sum up, there are two different diodes you need to know about: regular diodes and a light-emitting diodes (LEDs). They have different roles in circuits, and different circuit symbols.

What is the circuit symbol for diodes meant to represent? Diodes have very high resistance in one direction, so the current only flows in one direction through the diode. This is shown by the circuit symbol. The arrow shows the direction that the current can flow through it.

What is the role of an LED in a circuit? Which part of the circuit symbol shows that an LED emits light? 1

Here we can see two complete circuit diagrams.

They each include a cell, a motor and a diode. 2

Will the current flow in the same direction in these two circuits? Answer yes or no.  3

The role of a diode is to only allow current to flow in one direction.

The diode in circuit A is connected in the opposite direction to the diode in circuit B, therefore they regulate the direction of the current in reverse to each other. 