Follow energy transfers and spot wasted energy

Question 1

Every second, an LED lamp is supplied with 1000 J of energy. 750 J is transferred usefully (light). How much energy is wasted each second, in J?

Answer J

Question 2

A car brakes and stops. Where does most of its kinetic energy go?

• A. the chemical store of the fuel
• B. the car's gravitational store
• C. the thermal store of the brakes and surroundings
• D. it disappears

Question 3

Energy transfers: which statement is true?

• A. Wasted energy usually ends up heating the surroundings.
• B. Wasted energy is destroyed.
• C. An LED lamp transfers all its energy to light.
• D. Machines can give out more energy than they take in.

Question 4

Every second, an electric kettle is supplied with 2000 J of energy. 400 J is transferred usefully (heating the water). How much energy is wasted each second, in J?

Answer J

Question 5

A torch (flashlight) is switched on. Which describes the main energy transfer?

• A. chemical store of the battery → electrically → light and heating the surroundings
• B. light → battery
• C. thermal store → chemical store
• D. kinetic store → nuclear store

Question 6

Energy transfers: which statement is true?

• A. Machines can give out more energy than they take in.
• B. An LED lamp transfers all its energy to light.
• C. Wasted energy is destroyed.
• D. Lubrication can reduce wasted energy in machines.

Question 7

Every second, a drill is supplied with 1200 J of energy. 480 J is transferred usefully (turning the drill bit). How much energy is wasted each second, in J?

Answer J

Question 8

Some electric cars use regenerative braking. What does this do?

• A. creates new energy from nothing
• B. transfers kinetic energy back into the battery's chemical store
• C. stops the car using air only
• D. makes the brakes hotter

Question 9

Energy transfers: which statement is true?

• A. An LED lamp transfers all its energy to light.
• B. Machines can give out more energy than they take in.
• C. The total energy before and after a transfer is the same.
• D. Wasted energy is destroyed.

Question 10

Every second, an LED lamp is supplied with 1200 J of energy. 480 J is transferred usefully (light). How much energy is wasted each second, in J?

Answer J

Question 11

Some electric cars use regenerative braking. What does this do?

• A. makes the brakes hotter
• B. creates new energy from nothing
• C. transfers kinetic energy back into the battery's chemical store
• D. stops the car using air only

Question 12

Energy transfers: which statement is true?

• A. Wasted energy is destroyed.
• B. An LED lamp transfers all its energy to light.
• C. Machines can give out more energy than they take in.
• D. Wasted energy usually ends up heating the surroundings.

Question 13

Every second, a phone speaker is supplied with 100 J of energy. 90 J is transferred usefully (sound). How much energy is wasted each second, in J?

Answer J

Question 14

Which is a way energy is TRANSFERRED, not a store?

• A. thermal
• B. kinetic
• C. chemical
• D. by electric current

Question 15

Energy transfers: which statement is true?

• A. Wasted energy is destroyed.
• B. Lubrication can reduce wasted energy in machines.
• C. Machines can give out more energy than they take in.
• D. An LED lamp transfers all its energy to light.

Question 16

Every second, an electric fan is supplied with 500 J of energy. 200 J is transferred usefully (movement of the blades). How much energy is wasted each second, in J?

Answer J