Question

XWhy is resistanceproduced in anelectrical circuit?How is resistancemeasured?

Answer 1

Resistance is a measure of the opposition to the flow of current in an electrical circuit.

An electric current flows when electrons move through a conductor. The moving electrons collide with the electrons present in the metal. This makes it more difficult for the current to flow and causes resistance.

According to Ohm's law,

$V\propto I$

Here, V is the potential difference (voltage) and I is the current flowing in the circuit.

Removing the proportionality will give a constant as,

$V=RI$

Here, R is the resistance. Therefore,

$R=\frac{V}{I}$

It is measured in ohms (Ω).

Higher the current, lower will be the resistance and vice-versa.

The resistance of the given material is,

$\begin{gathered} R\propto L \\ R\propto\frac{1}{A} \end{gathered}$

Therefore,

$R=\rho\frac{L}{A}$

Here, L is the length of the conductor, A is the area of the conductor and ρ is the resistivity of the conductor.