Electrical resistance of any object is:

The electrical resistance of any object is directly proportional to its length and inversely proportional to its area of cross-section.


When an electric current flows through a bulb or any conductor, the conductor offers some obstruction to the current and this obstruction is known as electrical resistance and is denoted by R.  As per ohm’s law, we know that

V ∝ I V = IR

V is the potential difference measured across the conductor (in volts)
I is the current through the conductor (in amperes)
R is the constant of proportionality called resistance (in ohms)

Factors affecting electrical resistance

The electrical resistance of a conductor is dependent on the following factors:

  • The cross-sectional area of the conductor
  • Length of the conductor
  • The material of the conductor
  • The temperature of the conducting material

Electrical resistance is directly proportional to the length (L) of the conductor and inversely proportional to the cross-sectional area (A). It is given by the following relation.

\(\begin{array}{l}R=\rho \frac{L}{A}\end{array} \)

where ρ is the resistivity of the material (measured in Ωm, ohm meter)



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