Question

Draw the circuit diagram of a Wheatstone bridge. Obtain the condition when no current flows through the galvanometer in it.

Assertion (A) : When electrons drift in a conductor, it does not mean that all free electrons in the conductor are moving in the same direction. Reason (R) : The drift velocity is superposed over large random velocities of electrons.

Assertion (A) : The current density (J) at a point in a conducting wire is in the direction of electric field (E) at that point. Reason (R) : A conducting wire obeys Ohm's law.

The radius of a conducting wire AB uniformly decreases from its one end A to another end B. It is connected across a battery. How will (i) electric field, (ii) current density, and (iii) mobility of electrons change from end A to end B ? Justify your answer in each case.