Look at the information about different electric motors - OCR Gateway - GCSE Physics - Question 18 - 2018 - Paper 1
Question 18
Look at the information about different electric motors.
Electric motor Energy input per hour (J) Useful energy output per hour (J) Energy 'wasted' per hour (J)
A 7... show full transcript
Worked Solution & Example Answer:Look at the information about different electric motors - OCR Gateway - GCSE Physics - Question 18 - 2018 - Paper 1
Step 1
Calculate the energy input per hour in J for electric motor D.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The energy input for electric motor D is already provided in the table as 60,000 J.
Step 2
Which electric motor has the lowest 'wasted' energy in one hour?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Electric motor E has the lowest 'wasted' energy, which is 6,000 J, calculated as follows:
Motor A: Wasted = 72,000 J - 60,000 J = 12,000 J
Motor B: Wasted = 54,000 J - 36,000 J = 18,000 J
Motor C: Wasted = 18,000 J - 3,000 J = 15,000 J
Motor D: Wasted = 48,000 J - 12,000 J = 36,000 J
Motor E: Wasted = 54,000 J - 48,000 J = 6,000 J
Step 3
Which electric motor has the highest 'wasted' energy in one hour?
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Electric motor D has the highest 'wasted' energy, which is 36,000 J.
Step 4
Describe how energy is 'wasted' in an electric motor.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Energy is 'wasted' in electric motors primarily as heat due to resistance in the windings, friction in the moving parts, and sound energy produced during operation. This wasted energy does not contribute to the useful work output of the motor.
Step 5
Suggest how this 'wasted' energy can be reduced in an electric motor.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To reduce 'wasted' energy in an electric motor, measures can include:
Lubrication: Reducing friction between moving parts through proper lubrication.
Improving Design: Utilizing efficient motor designs that minimize resistance in electrical components and aerodynamics.
Maintenance: Regular maintenance to ensure that all components are functioning optimally.
Step 6
Calculate the % efficiency of electric motor E.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To calculate the efficiency of electric motor E, use the formula:
extEfficiency=(Input energy transferUseful output energy transfer)×100
