Equipotential surfaces at a great distance from a collection of charges whose total sum is not zero are approximately
(a) spheres
(b) planes
(c) paraboloids
(d) ellipsoids
(a) spheres
(b) planes
(c) paraboloids
(d) ellipsoids
(a) spheres
The capacitance of a capacitor will decrease if we introduce a slab of:
(a) copper
(b) aluminium
(c) zinc
(d) None of these
The electric potential due to point charge 3 nC at distance of 9 cm is
(a) 270 v
(b) 3 v
(c) 300 v
(d) 30 v
Electric potential at a distance r from the point charge is proportional to
1. \(r^2\)
2. r-1
3. r0
4. r+1
In which of the following forms is the energy stored in a capacitor?
(a) Charge
(b) Potential
(c) Capacitance
(d) Electric field
The electrostatic potential energy between proton and electron separated by a distance of 1 Å is
(a) 13.6eV
(b) 27.2eV
(c) -14.4eV
(d) 1.44eV
A dielectric induces....... in an external electric field which decreases the net electric field.
(a) current
(b) dipole moment
(c) magnetic field
(d) polarisation
Why must electrostatic field at the surface of a charged conductor be normal to the surface at every point ? Give reason.
The idea of secondary wavelets for the propagation of a wave was first given by
(a) Newton
(b) Huygens
(c) Maxwell
(d) Fresnel
Two wires of same length are shaped into a square and a circle. If they carry same current, the ratio of their magnetic moment-
a) 2:π
b)π:2
c) 4:π
d) π:4.
Colours appears on a thin film of soap and a soap bubble is due to
(A) Interference
(B) Diffraction
(C) Polarisation
(D) Refraction
For any charge configuration equipotential surface through a point is normal to the electric field.
1. Since W=Fscosθ is zero so field is normal to the surface
2. As W≠0
3. Work done can be Zero if Field is parallel to the field
4. None of these
A coil of wire of certain radius has 500 turns and self inductance of 75 mH. The self inductance of a second similar coil of 600 turns will be
(a) 100 mH
(b) 150mH
(c) 108 mH
(d) 105mH
The magnetic flux linked with a coil is given by the equation Ø = 2t² + 2t + 4 weber. The magnitude of induced emf at time t=2s will be
(a) 16 V
(b) 10V
(c) 12V
(d) 8V
An alternating e.m.f. of angular frequency ω is applied across an inductance. The instantaneous power developed across it has an angular frequency
(a) ω/4
(b) ω/2
(c) ω
(d) 2 ω