Question

An electric motor must have which of the following in order to work?

A.galvanometer
B.power source
C. secondary coil
D.primary coil

Answer 1

B. Power Source

Step-by-step explanation:

Electric motor is a device which convert the electrical energy into mechanical energy.

In this device we have a coil of wire with N turns. When current flows through the coil then it will become a coil with finite magnetic moment.

It is given as

`M = N i A`

now this coil will experience the torque on the coil which is given by formula

`\tau = \vec M * \vec B`

due to this torque the coil start rotating so here main working of motor is to convert electrical energy into mechanical energy

So we provide the Power source to the coil from which it will get the electric current and then convert it into mechanical energy

so correct answer will be

B. Power Source

Answer 2

I am absolutely sure that when an electric motor must have B.power source. I choose the second option as the correct one because electric motor needs power source in order to perform it's main function - converting electrical energy into mechanical. Hope you will find it helpful!