K K Sharma Solutions for Chapter: Electromagnetic Induction, Exercise 16: AC Generator and Motor

The number of turns in the coil of an AC generator is $5000$ and the area of the coil is $0.25$ ${\mathrm{m}}^2$. The coil is rotated at the rate of $100$ cycles/s in a magnetic field of $0.2$ $\mathrm{Wb}/$${\mathrm{m}}^2$. The peak value of the emf generated is nearly,

The coil of a dynamo is rotating in a magnetic field. The developed induced emf changes and the number of magnetic lines of force also changes. Which of the following conditions is correct?

An electric motor operating on a $60 \mathrm{V}$ DC supply draws a current of $10 \mathrm{A}$. If the efficiency of the motor is $50\%$, the resistance of its winding is 

An electric motor operates on a $50 \mathrm{V}$ supply and a current of $12 \mathrm{A}$. If the efficiency of the motor is $30\%$, what is the resistance of the winding of the motor?

A motor having an armature of resistance $2 \mathrm{\Omega }$ is designed to operate at $220$ $\mathrm{V}$ mains. At full speed, it develops a back emf of $210 \mathrm{V}$. The current in the armature is 

Dynamo core is laminated because,

Armature current in a DC motor will be maximum when 

The armature of a DC motor has $20 \mathrm{\Omega }$ resistance. It draws a current of $1.5$ $\mathrm{A}$ when run by the $220$ $\mathrm{V}$ DC supply. The value of back emf induced in it will be