On moving a charge of 20 coulomb by 2 cm, 2 J of work is done, then the potential difference between the points is
0.1 V
8 V
2 V
0.5 V
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
The study of the effects associated with electric charges at rest is called
electromagnetism
electrostatics
magnetostatics
none of these
A capacitor connected to a 10 V battery collects a charge of 40 μC with air as dielectric, and 100 μC with oil as dielectric. The dielectric constant of oil is
2
8
2.5
1.5
Capacitance (in F) of a spherical conductor with radius 1 m is
1.1 × 10-10
10-6
9 × 10-6
10-3
The potential of a point A is -500 V and that of another point B is +500 V. The work done by an external agent to take 2 units of negative charge from B to A is
+1000 J
-1000 J
+2000 J
-2000 J
Electric potential of earth is taken to be zero because earth is a good
dielectric
semiconductor
insulator
conductor
Two spherical conductors A and B of radii 1 mm and 2 mm are separated by a distance of 5 cm and are uniformly charged. If the spheres are connected by a conducting wire then in 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
A charge q is placed at the centre of the line joining two exactly equal positive charges Q. The system of three charges will be in equilibrium, if q is equal to
- Q/4
+ Q
- Q
Q/2
A point charge + q is placed at midpoint of a cube of side L. The electric flux emerging from the cube is
zero
