Did this video help you?
Did this video help you?
The ratio of the useful energy output from a system to its total energy output
The blades of a fan are turned by an electric motor. In one second, 300 J of energy is transferred electrically from the mains supply to the fan. 85 J is wasted due to friction and sound.
Calculate the percentage efficiency of the motor.
Step 1: List the known quantities
Step 2: State the equation
Step 3: Determine total energy transferred by the device (output)
Step 4: Calculate the useful energy transferred by the device (output)
Step 5: Substitute these values into the efficiency equation
Efficiency can be in a ratio (between 0 and 1) or percentage format (between 0 and 100%)If the question asks for efficiency as a ratio, give your answer as a fraction or decimal.
If the answer is required as a percentage, remember to multiply the ratio by 100 to convert it:
Remember that efficiency has no units (only %)
Did this page help you?