Topic 2 - Electricity

Question 1

What is the function of a switch in a circuit?

Answer 1

used to turn a circuit on (closed) and off (open).

Question 2

What is the function of a fixed resistor in a circuit?

Answer 2

A resistor restricts or limits the flow of electrical current. Afixed resistorhas aresistancethat does not change.

Question 3

What is a variable resistor?

Answer 3

a resistor of which the electric resistance value can be adjusted

Question 4

What is a thermistor?

Answer 4

a component where resistance changes with its temperature

Question 5

with a thermistor, as the temperature increases the resistance ___________

Answer 5

decreases

Question 6

Name 2 things a thermistor can be used for

Answer 6

1. heat activated fire alarms
2. turn a heater of when the house turns a certain temperature

Question 7

What is a voltmeter used for?

Answer 7

measure voltage

Question 8

How is a voltmeter connected to a circuit?

Answer 8

in parallel

Question 9

What is an ammeter used for?

Answer 9

measure electric current

Question 10

How is an ammeter connected to a circuit?

Answer 10

in series

Question 11

What is an LDR (light dependant resistor)used for?

Answer 11

detect light levels

Question 12

With an LDR, as the light intensity increases, the resistance ___________

Answer 12

decreases

Question 13

What can LDR’s be used for?

Answer 13

1. automatic lights
2. sensor in cameras

Question 14

what does a diode do?

Answer 14

allows current to flow in one direction only and are used to convert analternating currentinto adirect current.

Question 15

What is an LED (light emitting diode)used for?

Answer 15

emitts light when a current passes through it

Question 16

What does a fuse do?

Answer 16

a safety device that breaks the circuit (wire melts) if a fault in an appliance causes too much current to flow. This prevents overheating and possibly starting a fire.