Electricity

Class 10 NCERT Science

NCERT

1   What does an electric circuit mean?

Solution :

A continuous and closed path of an electric current is called an electric circuit. electric circuit consists of electric devices like switching devices, source of electricity, etc.

2   Define the unit of current.

Solution :

The unit of electric current is ampere (A).$1$A is defined as the flow of $1 $C of charge through a wire in $1$ s of time.

3   Calculate the number of electrons constituting one coulomb of charge.

Solution :

We know that charge is quantized i.e., Q = ne where n = number of electrons and e = charge of an electron , Therefore Given that$\\$ $Q=1C,e=1.6*10^{-19}C,n=?$$\\$ On substitution the above values in Q = ne, We get,$\\$ $1C=n*1.6*10^{-19}=\\ \dfrac{1}{1.6*110^{-19}}=\\ 6.25*10^{18}$$\\$ $=6*10^{18}$ electrons$\\$ Therefore, $6*10^{18 } $electrons constitute one coulomb of charge.

4   Name a device that helps to maintain a potential difference across a conductor.

Solution :

A source of electricity such as cell, battery, power supply, etc. helps to maintain a potential difference across a conductor.

5   What is meant by saying that the potential difference between two points is $1 V$?

Solution :

If $1 J$ of work is required to move a charge of amount $1 C$ from one point to another,then it is said that the potential difference between the two points is $1 V$.