ScienceAges 10-12

Percentage energy efficiency

Calculate the percentage efficiency of a device from useful energy output and total energy input. Review suitability for your learners before teaching.

New variation Try interactive challenge Browse templates

Age band:Ages 10-12 Ages 13-15

Choose “Save as PDF” to keep a copy. Use your browser’s paper setting for A4 or Letter.

Worksheet StudioPractice pack · Ages 10-12

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 260 J of total energy and transfers 195 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 195 J · Wasted: 65 J
2. A machine is supplied with 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 153 J · Wasted: 27 J
3. A machine is supplied with 180 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 72 J · Wasted: 108 J
4. A machine is supplied with 180 J of total energy and transfers 171 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 171 J · Wasted: 9 J
5. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 72 J · Wasted: 48 J
6. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 42 J · Wasted: 78 J
7. A machine is supplied with 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 176 J · Wasted: 264 J
8. A machine is supplied with 220 J of total energy and transfers 55 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 55 J · Wasted: 165 J
9. A machine is supplied with 60 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 45 J · Wasted: 15 J
10. A machine is supplied with 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 64 J · Wasted: 96 J
11. A machine is supplied with 80 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 64 J · Wasted: 16 J
12. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 48 J · Wasted: 112 J

12 questions · Seed 43 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 10-12

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 260 J of total energy and transfers 195 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (195 ÷ 260) × 100% = 75%.
2. A machine is supplied with 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (153 ÷ 180) × 100% = 85%.
3. A machine is supplied with 180 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 180) × 100% = 40%.
4. A machine is supplied with 180 J of total energy and transfers 171 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (171 ÷ 180) × 100% = 95%.
5. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 120) × 100% = 60%.
6. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (42 ÷ 120) × 100% = 35%.
7. A machine is supplied with 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (176 ÷ 440) × 100% = 40%.
8. A machine is supplied with 220 J of total energy and transfers 55 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (55 ÷ 220) × 100% = 25%.
9. A machine is supplied with 60 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (45 ÷ 60) × 100% = 75%.
10. A machine is supplied with 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 160) × 100% = 40%.
11. A machine is supplied with 80 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 80) × 100% = 80%.
12. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 160) × 100% = 30%.

12 questions · Seed 43 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 10-12

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 260 J of total energy and transfers 195 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 195 J · Wasted: 65 J
2. A machine is supplied with 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 153 J · Wasted: 27 J
3. A machine is supplied with 180 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 72 J · Wasted: 108 J
4. A machine is supplied with 180 J of total energy and transfers 171 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 171 J · Wasted: 9 J
5. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 72 J · Wasted: 48 J
6. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 42 J · Wasted: 78 J
7. A machine is supplied with 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 176 J · Wasted: 264 J
8. A machine is supplied with 220 J of total energy and transfers 55 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 55 J · Wasted: 165 J
9. A machine is supplied with 60 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 45 J · Wasted: 15 J
10. A machine is supplied with 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 64 J · Wasted: 96 J
11. A machine is supplied with 80 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 64 J · Wasted: 16 J
12. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 48 J · Wasted: 112 J

12 questions · Seed 43 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 10-12

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 260 J of total energy and transfers 195 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (195 ÷ 260) × 100% = 75%.
2. A machine is supplied with 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (153 ÷ 180) × 100% = 85%.
3. A machine is supplied with 180 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 180) × 100% = 40%.
4. A machine is supplied with 180 J of total energy and transfers 171 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (171 ÷ 180) × 100% = 95%.
5. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 120) × 100% = 60%.
6. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (42 ÷ 120) × 100% = 35%.
7. A machine is supplied with 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (176 ÷ 440) × 100% = 40%.
8. A machine is supplied with 220 J of total energy and transfers 55 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (55 ÷ 220) × 100% = 25%.
9. A machine is supplied with 60 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (45 ÷ 60) × 100% = 75%.
10. A machine is supplied with 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 160) × 100% = 40%.
11. A machine is supplied with 80 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 80) × 100% = 80%.
12. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 160) × 100% = 30%.

12 questions · Seed 43 · Age guidance, not curriculum certification