Question

An Inductor L, resistance R, battery B and switch S are connected in series. Voltmeters ${V_L}$ and ${V_R}$ are connected across L and R respectively, When S is closed
(A) The initial reading in ${V_L}$ will be greater than ${V_R}$
(B) The initial reading in ${V_L}$ will be lesser than ${V_R}$
(C) The initial readings in ${V_L}$ and ${V_R}$ will be same
(D) The reading in ${V_L}$ will decrease as time increases

Answer 1

Hint: Inductor hates sudden change it opposes very strongly when some sudden change happens so when switch S is closed the inductor will oppose and there will be no current in the circuit and it will produce a voltage in the opposite direction of magnitude same as applied voltage. Meanwhile the capacitor stays calm and gets charged slowly.

Complete step by step answer:
When switch is open there is no current in the circuit but when we close the switch at the very moment current will be zero because inductor won’t allow it by producing potential difference of same magnitude in opposite direction so at $t = 0$ ${V_L}$ will be maximum and ${V_R}$ will be zero and
As time passes the capacitor will get charged and it will develop potential meanwhile potential difference produced by the inductor will decrease and finally it will become zero so at $t = \infty $ ${V_L}$ will be zero and ${V_R}$ will be maximum.

Hence, Option-A and Option-D are correct.

Note: In order to solve such types of questions you need to understand how the inductor and capacitor reacts to change. For future reference remember this (at $t = 0$capacitor acts as a plane wire while inductor acts as an open wire and at $t = \infty $ inductor acts as plane wire and capacitor acts as an open wire).