In the following circuit diagram, when $ 3 \Omega $ resistor is removed, then equivalent resistance of the network

A conducting wire is stretched by applying a deforming force, so that its diameter decreases to $ 40 \% $ of original value. The percentage change in its resistance will be

The power dissipated in the circuit shown in the figure $$40 \mathrm{~W}$$. The value of $$R$$ is.

In the arrangement shown in figure, when the switch S₂ is open, the galvanometer, shows no deflection for $$l$$ = 50 cm when the switch S₂ is closed, the galvanometer shows no deflection for $$l$$ = 0.416 m. The internal resistance (r) of 6 V cell is