Question

Name some devices in which electric motors are used.

Answer 1

Hint: Electric motors are devices that convert electrical energy into mechanical energy and bring about rotation of an object. This is because, when a current carrying coil is placed in a magnetic field, it experiences a torque that tries to rotate the coil such that the perpendicular to the surface of the coil is parallel with the magnetic field.

Formula used:
$\tau =NAIB\sin \theta $
Where $\tau $ is the magnitude of the torque on a coil of $N$ turns and cross sectional area $A$ and carrying a current $I$ when it is placed in a magnetic field of magnitude $B$. $\theta $ is the angle made by the perpendicular to the cross sectional area of the coil with the magnetic field.

Complete step by step answer:
Electric motors convert electrical energy into rotational mechanical energy by using the principle that a current carrying coil placed in a magnetic field experiences a torque.
The magnitude of this torque is given by
$\tau =NAIB\sin \theta $
Where $\tau $ is the magnitude of the torque on a coil of $N$ turns and cross sectional area $A$ and carrying a current $I$ when it is placed in a magnetic field of magnitude $B$. $\theta $ is the angle made by the perpendicular to the cross sectional area of the coil with the magnetic field.
Electric motors are employed in many devices which require rotational output. For example, a fan rotates due to an electric motor rotating the shaft of the fan when electricity passes through it.
Washing machines also employ the same principle to rotate the tumbler inside the washing machine.
Mixer grinders also have an electric motor that rotates the shaft connected to the blades in the mixer grinder.

Note: Students often confuse between electric motors and electric generators. However, they are essentially the opposites of each other. Electric motors convert electrical energy into rotational mechanical energy whereas electric generators do the exact opposite by converting rotational mechanical energy input to electrical energy output.
It might be of interest to students to know that electrical energy is the easiest form of energy to control and transmit. Hence, we use electrical energy in our homes and industries. Electrical generators are used to convert other forms of energy into by first converting the other form of energy into rotational mechanical energy and then ultimately to electrical energy.