Heat dissipated by a conductor when a current is passed through it is directly proportional to the resistance of the conductor.

What is the practical unit used for electrical energy?

When three resistors of $5 \Omega$,$10 \Omega$,and $30 \Omega$ are connected in parallel in a circuit,what will be the equivalent resistance?

$A$ wire is $1.0 \, m$ long,$0.2 \, mm$ in diameter and has a resistance of $10 \, \Omega$. Calculate the resistivity of its material.

$A$ piece of wire of resistance $6 \, \Omega$ is connected to a battery of $12 \, V$. Find the amount of current flowing through it. Now,the same wire is redrawn by stretching it to double its length. Find the resistance of the new (redrawn) wire.

Define resistance of a conductor. State the factors on which resistance of a conductor depends. Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.
Calculate the resistance of $50 \, m$ length of wire of cross-sectional area $0.01 \, mm^2$ and of resistivity $5 \times 10^{-8} \, \Omega \, m$.