Electricity

*Electric Current
An electric current is defined as the amount of charge flowing through any cross section of a conductor per unit time. I= Q/t.

* Electric current in terms of number of electrons(n) in a conductor , I= ne/t
e=1.6 x 10-19 C

* S.I unit of current is AMPERE(A).

* Ampere(A) Elevtric current through a conductor is said to be 1 ampere of one coulomb charge flows through any cross section in one second.

* Ammeter is uded to measure domestic circuits.

* Electric current is a scalar quantity.

*Electric potential is defined as work done per unit charge.
V= W/q

* S.I unit of electric potential is VOLT(V)

*Voltmeter is used to measure the potential difference between two points in an electric circuits.

* voltmeter is always connected in parallel in an electric circuits.

*Ohm's law
This law states that " electric current flowing in a conductor is directly proportional to the potential difference acreoss the ends of the conductor, provided the temperature and other physical conditions of the conductor remains the same."
V= I x R


* The graph for ohms law is a straight line.


Circuit of ohms law


* Resistance
It is the ability of the conductor to oppose the flow of charge through it.

* Unit of reistance is Ohm.

* Resistance of a conductor is said to be 1 Ohn if a potential differnce of 1 Volt across the ends of the conductor produces a current of 1 ampere through it.

* Laws of resistance
1) Depends on the nature of the material of the conductor.
2) Directly propirtional to the length of the conductor.
3) inversely proportional to the area of the cross section.
4) increases with temperature and decrease with decrease in temperature.