Generator

A current that always flows through an electric device in the same direction is called direct current or $\mathrm{DC}$. The polarity (positive and negative) of a direct current is fixed. A current that reverses direction at equal intervals of time is called the alternating current or $\mathrm{AC}$. The polarity (positive and negative) of an alternating current is not fixed. Both $\mathrm{DC}$ and $\mathrm{AC}$ can be used for lighting and heating. Some electric devices like the television need $\mathrm{DC}$ to operate. In such cases, an adapter or a device is fitted into them to convert $\mathrm{AC}$ from the mains supply to $\mathrm{DC}$.

On the basis of above information, answer the following :

A current that always flows through an electric device in the same direction is called direct current or $\mathrm{DC}$. The polarity (positive and negative) of a direct current is fixed. A current that reverses direction at equal intervals of time is called the alternating current or $\mathrm{AC}$. The polarity (positive and negative) of an alternating current is not fixed. Both $\mathrm{DC}$ and $\mathrm{AC}$ can be used for lighting and heating. Some electric devices like the television need $\mathrm{DC}$ to operate. In such cases, an adapter or a device is fitted into them to convert $\mathrm{AC}$ from the mains supply to $\mathrm{DC}$.

On the basis of above information, answer the following :

What is the use of armature in an electric motor?

The frequency of an a.c. generator depends upon:

The below graph represents AC current.

Differentiate the DC and AC current graphically.

Explain the DC current graphically.

Explain the AC current graphically.

Armature of the electric motor is a current carrying loop.

When armature rotates, axle also rotates. 

An AC generator is connected to an electric appliance. In $10$ revolutions of the armature, how many times the current in the appliance changes direction?

An AC generator is connected to an electric appliance. In $5$ revolutions of the armature, the current in the appliance changes direction

In $10$ revolutions of the armature the current in the appliance will change direction _____ times.

What is the difference between alternating current generator and direct current generator?

A circular coil of radius $6 \mathrm{c}\mathrm{m}$ and $20$ turns rotates about its vertical diameter with an angular speed of $40\mathrm{ }\mathrm{r}\mathrm{a}\mathrm{d}\mathrm{ }{\mathrm{s}}^{-1}$, in a uniform horizontal magnetic field of magnitude $2\times {10}^{-2} \mathrm{T}$ . If the coil forms a closed loop of resistance $8 \mathrm{\Omega }$ , then the average power loss due to joule heating is