The resistance of a wire is $R$. If the length of the wire is doubled by stretching,then the new resistance will be

The resistance of a wire at $0^{\circ} C$ is $20 \Omega$. If the temperature coefficient of resistance is $5 \times 10^{-3} {}^{\circ} C^{-1}$,the temperature at which the resistance will be double that at $0^{\circ} C$ is: (in $^{\circ} C$)

$A$ wire of resistance $R$ is stretched until its radius is halved. What will be the new resistance (in $, R$)?

The dimension of $\sqrt{\frac{\mu_0}{\epsilon_0}}$ is equal to that of (where $\mu_0 = \text{vacuum permeability}$ and $\epsilon_0 = \text{vacuum permittivity}$)

The resistance of a conductor increases with:

If copper and silicon are cooled from $300 \, K$ to $60 \, K$,their resistivity will: