The Atlantic torpedo is a large electric fish capable of generating a voltage of 220 V between its tail and its head.

Question 7

The Atlantic torpedo is a large electric fish capable of generating a voltage of 220 V between its tail and its head. This drives a pulse of current of 15 A lasting for a time of 2.0 ms. The fish produces 200 pulses per second.

What is the average power output of the fish?

A 33 W                        B 1.3 kW                     C 3.3 kW                     D 6.6 kW

Reference: Past Exam Paper – November 2015 Paper 11 Q33

Solution:

Answer: B.

A pulse of current of 15 A lasts for 2.0 ms.

Power = VI                 and Power = Energy / time

Energy = Power × time

Energy of each pulse = VIt

Energy of each pulse = 220 × 15 × 2.0×10^-3 = 6.6 J

The fish produces 200 pulses per second (this quantity is the number of pulses per second).

Average power = total energy / time

Average power = no. of pulses × energy of 1 pulse / time

Average power = (no. of pulses / time) × energy of 1 pulse

(no. of pulses / time) = 200 s^-1

Average power = (no. of pulses / time) × energy of 1 pulse

Average power = 200 × 6.6

Average power = 1320 W = 1.3 kW