Efficiency
1.7.4What the syllabus asks of you
- Define efficiency as: (a) (%) efficiency = (useful energy output) / (total energy input) ( × 100%) (b) (%) efficiency = (useful power output) / (total power input) ( × 100%) and recall and use these equations
Read the notes first
Chapter 1: Efficiency
Drill this topic
Every question on Efficiency, untimed, marked as you go.
Make a worksheet
Choose the years and how many questions, then print it with the answers on separate pages.
20 questions
1May / June 2026 · Paper 11 · Q13Show mark scheme →
A13 W
B75 W
C1300 W
D48 000 W
Mark scheme
2Oct / Nov 2025 · Paper 12 · Q17Show mark scheme →
Aefficiency = \frac{\text{useful energy input}}{\text{total energy output}}
Befficiency = \frac{\text{total energy input}}{\text{total energy output}}
Cefficiency = \frac{\text{useful energy output}}{\text{total energy input}}
Defficiency = \frac{\text{total energy output}}{\text{total energy input}}
Mark scheme
3Oct / Nov 2024 · Paper 11 · Q18Show mark scheme →
A\frac{14}{74}
B\frac{14}{60}
C\frac{14}{46}
D\frac{46}{60}
Mark scheme
4Oct / Nov 2024 · Paper 12 · Q11Show mark scheme →
Aefficiency = useful energy output / total energy input
Befficiency = total energy input / useful energy output
Cefficiency = total energy output / total power input
Defficiency = (useful energy output) × (total energy input)
Mark scheme
5May / June 2024 · Paper 11 · Q13Show mark scheme →
A0.15
B0.45
C0.55
D0.85
Mark scheme
6May / June 2024 · Paper 12 · Q16Show mark scheme →
A0.26
B0.35
C0.59
D0.74
Mark scheme
7Oct / Nov 2023 · Paper 12 · Q14Show mark scheme →
Aefficiency = \frac{\text{GPE gained per second}}{\text{KE gained per second}}
Befficiency = \frac{\text{GPE gained per second}}{\text{power supplied}}
Cefficiency = \frac{\text{power supplied}}{\text{GPE gained per second}}
Defficiency = \frac{\text{power supplied}}{\text{KE gained per second}}
Mark scheme
8Oct / Nov 2022 · Paper 11 · Q16Show mark scheme →
AX is more expensive to run.
BX has a lower electrical resistance.
CX produces less light energy.
DX produces less thermal energy.
Mark scheme
9Oct / Nov 2022 · Paper 12 · Q17Show mark scheme →
A18%
B22%
C55%
D82%
Mark scheme
10Oct / Nov 2022 · Paper 12 · Q18Show mark scheme →
Asound only
Bthermal only
Cthermal and chemical
Dthermal and sound
Mark scheme
11May / June 2022 · Paper 11 · Q11Show mark scheme →
A6.0, 17
B0.17, 6.0
C6.0, 6.0
D0.17, 17
Mark scheme
12May / June 2022 · Paper 12 · Q15Show mark scheme →
A0.10
B0.90
C0.925
D0.975
Mark scheme
13Oct / Nov 2021 · Paper 12 · Q13Show mark scheme →
Aefficiency = useful energy output / total energy input
Befficiency = total energy input / useful energy output
Cefficiency = energy converted to the required form / total power input
Defficiency = (energy converted to the required form) × (total energy input)
Mark scheme
14May / June 2021 · Paper 11 · Q14Show mark scheme →
A1.6 kW
B2.2 kW
C64 kW
D160 kW
Mark scheme
15Oct / Nov 2020 · Paper 11 · Q19Show mark scheme →
Ahydroelectric; nuclear
Bhydroelectric; oil
Cnuclear; hydroelectric
Doil; hydroelectric
Mark scheme
16May / June 2019 · Paper 12 · Q19Show mark scheme →
A11%
B17%
C52%
D80%
Mark scheme
17Oct / Nov 2018 · Paper 11 · Q9Show mark scheme →
AIncrease the friction in the motor.
BReduce the energy losses in the motor.
CUse a fuse with a higher current rating.
DUse a fuse with a lower current rating.
Mark scheme
18Oct / Nov 2018 · Paper 12 · Q12Show mark scheme →
A0.040 s
B0.25 s
C4.0 s
D40 s
Mark scheme
19May / June 2017 · Paper 11 · Q15Show mark scheme →
A0.18 kW
B1.8 kW
C3.0 kW
D180 kW
Mark scheme
20Oct / Nov 2016 · Paper 12 · Q16Show mark scheme →
A\frac{\text{electrical energy output}}{\text{total energy input}}
B\frac{\text{electrical energy output}}{\text{thermal energy output}}
C\frac{\text{total energy output}}{\text{electrical energy input}}
D\frac{\text{thermal energy output}}{\text{total energy input}}
Mark scheme