Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is

Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 volt and the average resistance per km is 0.5 $$\Omega $$. The power loss in the wire is

The resistances in the two arms of the meter bridge are 5 $$\Omega $$ and R$$\Omega $$ respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6$$l$$₁. The resistance R is

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of 2.0 V and a negligible internal resistance. The potentiometer wire itself is 4 m long. When the resistance R, connected across the given cell, has values of (i) infinity,    (ii) 9.5 $$\Omega $$
the balancing lengths on the potentiometer wire are found to be 3 m and 2.85 m, respectively. The value of internal resistance of the cell is