Physics 2001 JAMB Past Questions - Question 27: A working electric motor takes a current of 1.5 A when the p.d. across it is 250 V. If its efficiency is 80%, the power output is

Correct Answer

A

Explanation

80=output/1.5*250 *100 ;output =300WTo find the power output of the electric motor, you can use the formula for power:

Power (P) = Current (I) × Voltage (V)

Given:
Current (I) = 1.5 A
Voltage (V) = 250 V

First, calculate the input power (P_input):

P_input = I × V
P_input = 1.5 A × 250 V
P_input = 375 W

Now, you mentioned that the efficiency of the motor is 80%. Efficiency is defined as:

Efficiency (η) = (Useful Output Power) / (Input Power)

You want to find the useful output power (P_output), so rearrange the formula to solve for P_output:

Useful Output Power (P_output) = Efficiency (η) × Input Power (P_input)

Substitute the values:

P_output = 0.80 × 375 W
P_output = 300 W

So, the power output of the electric motor is 300 watts (W) when its efficiency is 80%.