### Ohms law class 10

Sunday, 23 February 2020

laws
# Ohms law class 10

## Ohm's law:-

At constant temperature and pressure ( physical condition remains same ) the current passing through the conductor is directly proportional to the potential difference across its ends.

**This explain as follows:-**

Ohm's law means temperature and pressure of conductor ( where electric current flow through it ) remains constant at all time until potential difference or voltage of conductor increases with increase electric current if no increase in electric current only voltage increase then the temperature of the conductor increase then, this will not follow the law of ohm's law.

**According to ohm's law**

Electric current ⋉ potential difference

I ⋉ V

From above explanation we conclude that

potential difference between two ends ⋉ current passing through the conductor

V ⋉ I

V = IR

R = V / I

where R is constant called resistance

- S.I unit of resistance is ohm Ω.
- we find that the ratio of the potential difference and the current flowing through the conductor is a constant quantity called resistance.
- the current is directly proportional to the potential difference.
- the current is inversely proportional to the resistance.
- If potential difference is double the electric current get double.
- If resistance is double then the electric current get halved.
- If potential difference is 1 V and current is 1 A then the resistance is 1 Ω.
- The conductor which obey the ohm's law are called the ohmic conductor or linear resistance.
- All metallic conductor such as silver, Aluminium, copper, Iron, etc. are the ohmic conductor.
- All conductor which do not obey the ohm's law are called the non ohmic conductor or non linear resistance.

## Limitation of ohm's law

- Ohm's law does not apply to the conductor such as diode, Radio, electricity through gas etc.
- Ohm's law is applicable only when the physical condition remains constant.

## Factor affecting resistance

The resistance of a conductor depends on temperature, Nature of material medium, length, and the cross sectional area.

**Temperature:-**If resistance of the wire at 0 °C be R or if resistance of the wire increase then the temperature also increases.

**Nature of material medium:-**It has been found that if two resistor made up of the same length and same area of cross section but different material then the resistance is different.

**Length:-**If the length of the wire increase then the resistance also increases.

**Area of cross section:-**If area of cross section increase then the resistance decreases.