P1.3 The usefulness of electrical appliances

Question 1

What does the amount of energy an appliance transfers depend on? (2)

Answer 1

• How long the appliance is switched on

- Its power

Question 2

In the equation ‘E=P x t’ what are the units for each of the letters? There are two possible units for each

Answer 2

E= kWh, Joules
P=kW, Watts
t=hours, Seconds

Question 3

What can these equations help us to calculate?

Answer 3

The cost of mains electricity given the cost per kilowatt-hour

Question 4

How does a fan heater work?

Answer 4

BLOWS WARM AIR from hot element around the room

Question 5

How does a radiant heater work?

Answer 5

Uses a REFLECTOR to direct radiation from the GLOWING ELEMENT

Question 6

How does a tubular heater work?

Answer 6

The heater element is INSIDE a METAL TUBE which heats the room

Question 7

What is a disadvantage of a fan heater?

Answer 7

Energy is needed to run the fan motor

Question 8

What is a disadvantage of a radiant heater?

Answer 8

Only heats air and objects in front of the heater

Question 9

What is a disadvantage of a tubular heater?

Answer 9

Provides background heat gradually

Question 10

What are the two shared disadvantages of filament bulbs and halogen bulbs?

Answer 10

• Innefficient

- Gets hot

Question 11

What are two disadvantages of low-energy compact fluorescent bulbs? (2)

Answer 11

• Takes a few minutes for full brightness

- Disposal must be in a SEALED BAG (because of toxic mercury)

Question 12

What are the disadvantages of low-energy light-emitting diodes? (2)

Answer 12

• Expensive to buy

- Need several to get to the brightness of one halogen bulb

Question 13

Which two light bulbs are used for room lighting?

Answer 13

• Filament bulbs

- Low-energy compact fluorescent bulbs

Question 14

Which two light bulbs are used for spotlights?

Answer 14

• Halogen bulbs

- Low-energy light emitting diode