The wire of length $L$ and resistance $R$ is stretched so that the radius of its cross-section is halved. What is its new resistance?

Five dry cells each of voltage 1.5 V are connected as shown in diagram

What is the overall voltage with this arrangement?

In given circuit diagram two resistors are connected to a $5V$ supply: Calculate potential difference across the $8\Omega$ resistor.

In given circuit diagram two resistors are connected to a $5V$ supply. A third resistor is now connected in parallel with 6$\Omega$ resistor. Will the potential difference across the 8$\Omega$ resistor the larger, smaller or the same as before? Explain the reason for your answer.

Prove that the current density of a metallic conductor is directly proportional to the drift speed of electrons.