An electric motor can usefully convert 18 J of energy each second into kinetic energy to raise a mass above the ground. The motor has an input current of 2.5 A and an operating voltage of 16 V. Calculate the efficiency of the motor?

1 Answer
Junaid Mirza
May 12, 2018

#45%#

Explanation:

Input power of motor is

#"P"_i = "Vi = 16 volt × 2.5 A = 40 Watt"#

Output power of motor is

#"P"_o = "E"/"t" = "18 J"/"1 s" = "18 Watt"#

Efficiency (#eta#) of motor

#eta = "Output power"/"Input power" × 100#

#eta = (18 cancel"Watt")/(40 cancel"Watt") × 100 = 45%#

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