A Solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting spherical shell. Let the potential difference between the surface of the solid sphere and the outer of the shell be V. If the shell is given a charge -3Q the new potential difference between the same two surfaces is
1. 2V
2. V/2
3. V
4. -2V
1. 2V
2. V/2
3. V
4. -2V
3. V
Four point charges –Q,-q,2q,2Q are placed at different corners of a square . The relation between Q and q for which the potential at the center of the square is zero
1.Q=q
2.Q=1/q
3.Q=-q
4. Q=-1/q
An air capacitor is charged with an amount of charge q and dipped into an oil tank. If the oil is pumped out, the electric field between the plates of capacitor will
(a) increase
(b) decrease
(c) remain the same
(d) becomes zero
In the above diagram \(C_2\) is twice of Capacitance of \(C_1\) which is C. Find the ratio of energy stored in the combination before and after the insertion of of a dielectric constant K in both the capacitors.(Battery is disconnected)
Three concentric metallic shells A, B and C of radii a, b and c (a < b < c) have surface charge densities +σ, –σ and +σ respectively as shown in the figure.
Twenty-seven drops of mercury are charged simultaneously to the same potential of 10 volts. What will be potential if all the charged drops are made to combine to form one large drop ?
(a) 180 V
(b) 90 V
(c) 120 V
(d) 45 V
Write two properties of equipotential surfaces. Depict equipotential surfaces due to an isolated point charge. Why do the equipotential surfaces get closer as the distance between the equipotential surfaces and the source charge decreases ?
Find the P.E. associated with a charge q if it were present at the point P with respect to the ‘setup’ of two charged spheres, arranged as shown. Here O is the mid-point of the line O1O2.
To convert a moving coil galvanometer into on ammeter of given range, we must connect:
(a) A suitable low resistance in series
(b) A suitable low resistance in parallel
(c) A suitable high resistance in parallel
(d) A suitable high resistance in series
A tiny spherical oil drop carrying a net charge q is balanced in still air with a vertical uniform electric field strength 81/7 x 10⁵ Vm⁻¹. When the field is switched off, the drop is observed to fall with terminal velocity 2 x 10⁻³ ms⁻¹, given g = 9.8 ms⁻², viscosity of the air = 1.8 x 10⁻⁵ Nsm⁻², and the density of oil = 900 kgm⁻¹. The magnitude of q is.
(A) 1.6 x 10⁻¹⁹ C
(B) 3.2 x 10⁻¹⁹ C
(C) 4.0 x 10⁻¹⁹ C
(D) 8.0 x 10⁻¹⁹ C
Two-point charges 2μC and 4μC are placed 2 cm apart. The ratio of the Coulomb’s force experienced by them is
(A) 1: 2
(B) 2: 1
(C) 1: 1
(D) 4: 1
The coil of a moving coil galvanometer is wound over a metal frame in order to-
(a) reduce hysteresis
(b) increase sensitivity
(c) increase moment of inertia
(d) provide electromagnetic damping.
When ordinary light is made incident on a quarter wave plate, the emergent light is
(a) linearly polarised.
(b) circularly polarised.
(c) unpolarised.
(d) elliptically polarised.
A dielectric induces....... in an external electric field which decreases the net electric field.
(a) current
(b) dipole moment
(c) magnetic field
(d) polarisation