Question

The frequency of AC mains in India is:
(A) $30\,c{s^{ - 1}}$
(B) $50\,c{s^{ - 1}}$
(C) $60\,c{s^{ - 1}}$
(D) $120\,c{s^{ - 1}}$

Answer 1

Hint: The frequency of the alternating current is that which is the number of the cycles that can be completed in one second of the alternating current. The main frequency is the frequency of the alternating current that type of current is used in all types of domestic purposes.

Complete answer:
Generally, the frequency is defined as the number of cycles that can be completed in one second. And the alternating current has the sinusoidal waves, in alternating current the current will change its direction twice in one second. Basically, the countries which follow the European standard will use the $50\,Hz$ frequency range. Like that the Indian country also uses the same frequency range of $50\,Hz$as the frequency for its AC mains.
The alternating current changes its direction two time in the frequency, then
$ \Rightarrow 50 \times 2$
By multiplying the terms in the above equation, then the above equation is written as,
$ \Rightarrow 100\,Hz$
So, the alternating current of the frequency of the $100\,Hz$ is used. But the frequency of AC mains in India is $50\,Hz$. This amount of the frequency is used in our home application such as mobile charging and lap charging.
The unit of the frequency is Hertz and also it is expressed in cycles per second $\left( {c{s^{ - 1}}} \right)$.

Hence, the option (B) is the correct answer.

Note:
In addition to that the United states of America uses the $60\,Hz$ as the AC mains frequency. If the frequency of the AC mains keeps changing, it will lead to the damage of the electrical instruments when the switch is in on condition. So, it must be constant in all conditions.