1. Electronics

2. A light dependent resistor
A light dependent resistor can resist the flow of electricity through it

3. Set up the circuit: Lamp distance from LDR
What happens to the light bulb, how bright is it?
5cm
10cm
What is your conclusion about how the LDR works??

4. Light Dependent resistor
The amount of resistance it has depends on how much light is shining on the resistor.
The more light is shining on the LDR the more current it lets flow through it

5. Application of an LDR
LDRs are used as controls of street lamps

6. Electrical switches
A Switch can be used to complete or break a circuit

7. A diode
A diode allows electrical current to flow in one direction only.

8. Investigating a diode in a circuit
Which of these circuits will the bulb light up in?
What way should the diode be facing for electricity to flow?

9. Diode
When connected to a power supply it will only allow electricity to flow if it is forward facing

10. Applications of a diode in a circuit
Diodes are used to change alternating current to direct current in a circuit
In an a.c power supply the electricity is constantly changing direction of flow!
The diode will only allow the electricity to flow when it flowing in one particular direction!

11. LED An LED is a diode that emits light as current passed through them.
Symbol

12. LEDS
LED’s are often used as power indicators on radios, TV’s and other electronic devices.
LED’s are used instead of bulbs as they need less current to work!!