Questions in Current Electricity

Select	Question
	What length of the wire of specific resistance $48\times 10^{-8}\mathrm{\Omega m}$ is needed to make a resistance of $4.2 \Omega$ (diameter of wire = 0.4 mm)
	A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of
	The length of a given cylindrical wire is increased by 100 %. Due to the consequent decrease in diameter the change in the resistance of the wire will be
	Express which of the following setups can be used to verify Ohm’s law
	We have two wires A and B of same mass and same material. The diameter of the wire A is half of that B. If the resistance of wire A is 24 ohm then the resistance of wire B will be
	In a hydrogen discharge tube it is observed that through a given cross-section $3.13 \times 10^{15}$ electrons are moving from right to left and $3.12 \times 10^{15}$ protons are moving from left to right. What is the electric current in the discharge tube and what is its direction
	A steady current $i$ is flowing through a conductor of uniform cross-section. Any segment of the conductor has
	The length of the wire is doubled. Its conductance will be
	A source of e.m.f. E = 15 V and having negligible internal resistance is connected to a variable resistance so that the current in the circuit increases with time as $i = 1.2 t + 3$. Then, the total charge that will flow in first five second will be
	The new resistance of wire of R Ohm, whose radius is reduced half, is