Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions

Define electrostatic potential at a point. Write its S.I. unit. Three-point charges q1, q2 and q3 are kept respectively at points A, B, and C as shown in the figure, Derive the expression for the electrostatic potential energy of the system.

A point charge is placed at the centre of a hollow conducting sphere of internal radius ‘r’ and outer radius ‘2r’. The ratio of the surface charge density of the inner surface to that of the outer surface will be ______.

Derive the expression for the torque acting on an electric dipole, when it is held in a uniform electric field. identify the orientation of the dipole in the electric field, in which it attains a stable equilibrium.

A short bar magnet of magnetic moment m = 0.32 J T^–1 is placed in a uniform magnetic field of 0.15 T. If the bar is free to rotate in the plane of the field, which orientation would correspond to its

1. stable, and
2. unstable equilibrium?

What is the potential energy of the magnet in each case?

If the solenoid is free to turn about the vertical direction and a uniform horizontal magnetic field of 0.25 T is applied, what is the magnitude of torque on the solenoid when its axis makes an angle of 30° with the direction of applied field?

A circular coil of 16 turns and radius 10 cm carrying a current of 0.75 A rests with its plane normal to an external field of magnitude 5.0 × 10⁻² T. The coil is free to turn about an axis in its plane perpendicular to the field direction. When the coil is turned slightly and released, it oscillates about its stable equilibrium with a frequency of 2.0 s⁻¹. What is the moment of inertia of the coil about its axis of rotation?

Electric-field magnitude 'E' at points inside and outside a positively charged spherical conductor having charge Q and a radius R are ______.

If R is the radius of a spherical conductor, V_m the dielectric strength, then the maximum electric-field magnitude to which it can be raised is ______.

The instrument for the accurate measurement of the e.m.f of a cell is ______.

The instrument for the accurate measurement of the e.m.f of a cell is ______.

Kirchhoff’s second law is a consequence of law of conservation of ______.

Kirchhoff’s second law is a consequence of law of conservation of ______.

Figure shows current in a part of an electrical circuit. Then current I is ______.

Figure shows current in a part of an electrical circuit. Then current I is ______.

The electrostatic potential on the surface of a charged conducting sphere is 100V. Two statements are made in this regard S₁ at any point inside the sphere, electric intensity is zero. S₂ at any point inside the sphere, the electrostatic potential is 100 V. Which of the following is a correct statement?

The electrostatic force between the metal plates of an isolated parallel plate capacitor C having a charge Q and area A, is ______.

Assertion: Kirchhoff’s junction rule follows from conservation of charge.
Reason: Kirchhoff’s loop rule follows from conservation of momentum.

Assertion: Kirchhoff’s junction rule follows from conservation of charge.
Reason: Kirchhoff’s loop rule follows from conservation of momentum.