A pendulum bob of mass 30.7 x 10-6 kg and carrying a charge 2 x 10-8 C is at rest in a horizontal uniform electric field of 20000 V/m. The tension in the thread of the pendulum is (g = 9.8 m/s2).
3 x 104 N
4 x 10-4 N
5 x 10-4 N
6 x 10-4 N
A point charge + q is placed at midpoint of a cube of side L. The electric flux emerging from the cube is
zero
A cylinder of radius R and length L is placed in a uniform electric field E parallel to the axis of the cylinder. The total flux from the surface of cylinder is given by
2pR2E
Zero
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 100 μF capacitor is charged to a potential difference of 50 V, the charging battery then being disconnected. The capacitor is then connected to a second capacitor. If the measured potential difference drops to 35 V, the capacitance of the second capacitor is
52 μF
37 μF
59 μF
43 μF
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
Some charge is being given to a conductor, then its potential is
maximum at surface
maximum at centre
same throughout the conductor
maximum somewhere between surface and centre
The electric potential V at any point (x1, y1, z1) in space is given by V = 4x2 volt. The electric field at (1, 0, 2) m in Vm-1 is
8, along negative x-axis
8, along positive x-axis
16, along negative x-axis
16, along positive y-axis
A 4μF conductor is charged to 400 V and then its plates are joined through a resistance of 1 kΩ. The heat produced in the resistance is
0.16 J
1.28 J
0.64 J
0.32 J
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
4
8
2.5
1.5
