A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The Kinetic energy attained by the particle after moving a distance y is
q E y2
q E2 y
q E y
q2 E y
When air is replaced by a dielectric medium of constant K, the maximum force of attraction between two charges, separated by a distance.
decreases K times
increases K times
remains unchanged
becomes 1/K2 times
A point Q lies on the perpendicular bisector of an electric dipole of dipole moment p. If the distance of Q from the dipole is r, (much larger than the size of the dipole) then electric field at Q is proportional to
p-1 and r2
p and r-2
p2 and r-3
p and r-3
A hollow metal sphere of radius 10 cm is charged such that the potential on its surface is 80 V. The potential at the centre of the sphere is
zero
80 V
800 V
8 V
If the potential of a capacitor having capacity 6μF is increased from 10V to 20 V, then increase in its energy will be
4 x 10-4 J
4 x 10-14 J
9 x 10-4 J
12 x 10-6 J
The dielectric strength of air at NTP is 3 x 106 V/m. The maximum charge that can be given to a spherical conductor of radius 3 m is
3 x 104 C
3 x 10-3 C
3 x 10-2 C
3 x 10-1 C
Two spheres of radii r1 and r2 are charged to the same potential. If s1 and s2 are surface densities of charges on the two, then ratio is
Two spherical conductors A and B of radii 1mm and 2mm are separated by a distance of 5 cm and are uniformly charged. If the spheres are connected by a conducting wire then the equilibrium condition, the ratio of the magnitude of the electric fields at the surfaces of spheres A and B is
4 : 1
1 : 2
2 : 1
1 : 4
An electric dipole, consisting of two opposite charges of 2 x 10-6 C each separated by a distance 3 cm is placed in an electric field of 2 x 105N/C. Torque on the dipole is
12 x 10-1 Nm
12 x 10-2 Nm
12 x 10-3 Nm
12 x 10-4 Nm
Electric potential of earth is taken to be zero because earth is a good
dielectric
semiconductor
insulator
conductor
