Electricity In The Home And Electronics

Question 1

What are the colours of the earth, live and neutral wires in a plug?

Answer 1

Earth - Green and yellow
Neutral - Blue
Live - Brown

Question 2

What does a fuse do?

Answer 2

Does not allow current greater than its rating to flow through it or else it melts

Question 3

What does a circuit breaker do?

Answer 3

Trips off if the the current goes above a certain value

Question 4

What is a kilowatt-hour?

Answer 4

A unit of electrical energy converted by a 1 kW appliance running for 1 hour

Question 5

What is a diode?

Answer 5

A device which allows current to pass through it in one direction only

Question 6

What is a forward and reversed based diode?

Answer 6

Forward biased - Will conduct electricity

Reversed biased - Will NOT conduct electricity

Question 7

What are 2 uses of a diode?

Answer 7

As a rectifier and to protect appliances

Question 8

What does LED stand for?

Answer 8

Light Emitting Diode

Question 9

What is a cathode and an anode?

Answer 9

Cathode - negative end of a diode

Anode - positive end of a diode

Question 10

What are 3 uses for an LED?

Answer 10

Indicator lamps, digital displays, traffic lights

Question 11

What is an LDR?

Answer 11

Light Dependent Resistor

Question 12

How do you measure the resistance of a light dependent resistor as the brightness of the light shining on it varies?

Answer 12

1. Connect the LDR to the ohmmeter. Bring the lamp very close to the LDR and note he resistance
2. Vary the brightness of the light by gradually moving the lamp further from the LDR. Note the resistance on the ohmmeter after each change in brightness level
3. The resistance increases as the light as the brightness decreases

Question 13

Give 2 uses of LDRs

Answer 13

Switch street lighting, burglar alarms