CBSE Electricity Subject Notes

CBSE Guess > eBooks > Class X > Electricity by Mr Sunil D Chauhan

Electricity

Electricity

Electricity It is an important source of energy which is controllable and convenient for the uses in homes, hospitals, industries, etc.

Electric Current The amount of charge flowing through a particular area in unit time is called electric current.The SI unit of electric current is ampere and is denoted by 'A'. If 'Q' coulomb charge flows through a conductor in time 't', then

Electric Current = charge / time or I = Q / t or Q = I x t

One ampere When one coulomb charge flows through a conductor in 1 second, then the current flowing through it is called one ampere.

Electric charge The charge contained in one electron is called electric charge. The charge contained in about 6x10¹⁸electrons is called one coulomb of electric charge.

There are two types of electric charges - positive charges and negative charges. The important property of charges is that 'like charges repel each other' while 'unlike charges attract each other'.

The charge on one electron is 1.6x10^-19 coulomb. Number of electrons in one coulomb of charge.

1.6x10^-19coulomb     =     1 electron
1 coulomb                  =     1/1.6x10^-19electrons
                                     = 0.625x10¹⁹ electrons  = 6.25x10¹⁸ electrons

Direction of current The conventional direction of current is opposite to the direction of flow of electrons i.e. from positive electrode to the negative electrode. The direction of flow of electrons is from negative electrode to the positive electrode.

Electric circuit The arrangement of source of electric power, resistances, switches, and other elements connected together by wires is called an electric circuit.

Circuit diagrams The diagram which represents the different components connected in a circuit by using their symbols is called a circuit diagram.

Electric potential The work done in moving a unit positive charge from infinity to a given point is called electric potential.

Potential difference The amount of work done in moving a unit positive charge from one point to another point is called potential difference. Its SI unit is volt. It is represented by 'V'.

Potential difference = work done / charge (V = W/Q)

One volt If one joule work is done in moving one coulomb of electric charge from one point to the other, then the potential difference between the points is called one volt.

Ammeter The device which is used to measure the electric current in the circuit is called ammeter. It is represented by . . It is always connected in series in a circuit through which current is to be measured.

Voltmeter The device which is used to measure the potential difference across the ends of a resistor is calledvoltmeter. It is represented by. It is always connected in parallel across the resistor.

Ammeter has low resistance so that it may not change the value of current in the circuit.
Voltmeter has high resistance so that it may take the very less (negligible) current from the circuit.