Class 12 Chemistry Electrochemistry | Electrical resistance |

__Electrical resistance__

- It is denoted by the symbol
*‘***R**’. - It is measured in a unit called ohm (
**Ω**) with the help of a Wheatstone bridge - The electrical resistance is:

- Directly proportional to its length,
*l* - Inversely proportional to its area of cross section,
.*A*

- In the equation the constant of proportionality denoted by called rho is called
**resistivity.** - It is measured in units called ohm metre.
- When length = 1m.

Cross sectional area = 1m^{2}

- Then resistivitybecomes the resistance.

1 Ω m = 100 Ω cm

1 Ω cm = 0.01 Ω m

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