Title Physics ÔÇó Final Step-B ÔÇó VMC.pdf ✅

Vidyamandir Classes VMC | Final Step | Part - B 1 Class XII | Physics Final Step | Part - B | Physics Electrostatics CHOOSE THE CORRECT ALTERNATIVE. ONLY ONE CHOICE IS CORRECT. HOWEVER, QUESTIONS MARKED ‘*’ MAY HAVE MORE THAN ONE CORRECT OPTION. 1. A simple pendulum of length l has a bob of mass m, with a charge q on it A vertical sheet of charge, with surface charge density  passes through the points of suspension. At equilibrium, the string makes an angle  with the vertical, then : (A) 0 tan 2 q mg     (B) 0 tan q mg     (C) 0 cot 2 q mg     (D) 0 cot q mg     2. A charged particle of mass m and charge q is released from rest in an electric field of constant magnitude E. the kinetic energy of the particle after time t will be : (A) 2 2 2E t mq (B) 2 2 2 Eq m t (C) 2 2 2 2 E q t m (D) 2 Eqm t 3. A charge Q is distributed over two concentric hollow spheres of radius r and R (> r) such that the surface densities are equal. The potential at the common centre is: (A) 2 2 0 ( ) 4 ( ) Q R r R r    (B) Q R r  (C) Zero (D) 2 2 0 ( ) 4 ( ) Q R r R r    *4. If  0    s E .dS over a surface, then : (A) The electric field inside the surface and on it is zero (B) The electric field inside the surface is necessarily uniform (C) The number of flux lines entering the surface must be equal to the number of flux lines leaving it (D) Net charge, if any, must necessarily be outside the surface 5. The ratio of the forces between two small spheres with same charges when they are in air to when they are in a medium of dielectric constant K is : (A) 1: K (B) K :1 (C) 2 1: K (D) 2 K :1 6. Two point charges 2q and 8q are placed at a distance r apart. Where should a third charge q be placed between them so that the electrical potential energy of the system is a minimum : (A) At a distance of r/3 from 2q (B) At a distance of 2r/3 from 2q (C) At a distance of r/16 from 2q (D) None of these 7. A spherical conductor A of radius r placed concentrically inside a conducting shell B of radius R R r   . A charge Q is given to A, and then A is joined to B by a metal wire. The charge flowing from A and B will be : (A) R Q R r        (B) r Q R r        (C) Q (D) Zero