CLASS 10 / PHYSICS / ELECTRICITY( ELECTRIC CURRENT) / NOTES

Class 10 – Physics

 Ch 12 – Electricity

Subtopic – (12.1) Electric current and circuit

# STATIC AND CURRENT ELECTRICITY

Static electricity deals with the electric charges at rest while the current electricity deals with the electric charges in motion.

# CONDUCTOR

A substance which allows current to pass through it easily is called a conductor. It offers a low resistance to the flow of current. E.g. aluminum, copper, silver etc.

# INSULATOR

A substance with infinite high resistance and does not allow electric current to flow through it. E.g. glass, rubber, plastic etc.

# ELECTRIC CHARGE

     ·        It is physical property of matter.

     ·        Denoted by the letter ‘Q’

     ·        There are two types of electric charge – positive and negative (mostly carried out by electron and proton).

     ·         Electron are said to be carried negative charge and proton are said to carry positive charge.

     ·         By convection, the charge acquired by a glass rod rubbed with silk rod is called positive charge and the charge acquired by ebonite rod rubbed with a woolen cloth is called negative charge.

     ·         NOTE- Like charges repel and unlike charges attract each other.

# COULOMB

     ·        It is the S.I unit of charge.

     ·        Denoted as coulomb or ‘C’.

     ·        One coulomb is equivalent to the charge of approximately 6.242 x 10¹⁸ electrons.

     ·        Charge of an electron is -1.6 x 10^-19 and charge of proton is +1.6 x 10^-19.

     Thus, one coulomb = (6.242 x 10¹⁸) X (1.6 x 10^-19)

     ·        Also, charge accumulated on conductor, is given by

Q = n.e

Where, n = no. of electron

e = charge of an electron = 1.6 x 10^-19

          # ELECTRIC CURRENT

     ·        The flow of electric charge constitutes an electric current.

     ·        It is defined as the rate of flow of electric charge across a cross section of a conductor OR amount of charge flowing per unit time across a cross section of a conductor.

    Thus, electric current = charge accumulated / time taken

I = Q / t

Where, I = electric current

Q = electric charge

t = time taken

     ·        Electric current is a scalar quantity.

     ·        S.I unit of electric current is Ampere, denoted as ‘A’.

     ·        One ampere – if one coulomb of charge flows through any cross section of conductor in one second, then the current through the conductor is said to be one ampere.

1 ampere = 1 coulomb / 1 second

     ·        1 milli-ampere = 1 mA = 10^-3 A

     ·        1 microampere = 1 µA = 10^-6 A

# ELECTRIC CIRCUIT

The closed path along which electric current flows is called an electric circuit.

# CONVENTIONAL CURRENT

     ·        Conventionally, the direction of flow of positive charge is taken as the direction of electric current.

     ·        The conventional direction of electric current is from positive terminal of a battery to negative terminal of battery.

     ·        The actual flow of electron is from negative terminal of battery to positive terminal. Thus, direction of conventional current is opposite to the direction of flow of electrons.

# GALVANOMETER

It is a device used to detect current in an electric circuit.

# AMMETER

     ·        It is a device used to measure current in an electric circuit.

     ·        It is always connected in series in a circuit.

     ·        It should have low resistance.

KINDLY VISIT THE FOLLOWING LINK :

https://www.youtube.com/watch?v=8gvJzrjwjds

https://www.youtube.com/watch?v=D2monVkCkX4&t=212s