Science (English Medium) Class 12 - CBSE Question Bank Solutions for Physics

Consider the arrangement shown in the figure. By some mechanism, the separation between the slits S₃ and S₄ can be changed. The intensity is measured at the point P, which is at the common perpendicular bisector of S₁S₂ and S₂S₄. When \[z = \frac{D\lambda}{2d},\] the intensity measured at P is I. Find the intensity when z is equal to

(a) \[\frac{D\lambda}{d}\]

(b) \[\frac{3D\lambda}{2d}\]  and

(c) \[\frac{2D\lambda}{d}\]

The charge on a proton is +1.6 × 10⁻¹⁹ C and that on an electron is −1.6 × 10⁻¹⁹ C. Does it mean that the electron has 3.2 × 10⁻¹⁹ C less charge than the proton? 

When the separation between two charges is increased, the electric potential energy of the charges

The electric field at the origin is along the positive x-axis. A small circle is drawn with the centre at the origin, cutting the axes at points A, B, C and D with coordinates (a, 0), (0, a), (−a, 0), (0, −a), respectively. Out of the points on the periphery of the circle, the potential is minimum at  

If a body is charged by rubbing it, its weight

Consider the situation in the figure. The work done in taking a point charge from P to Ais W_A, from P to B is W_B and from P to C is W_C. 

A point charge q is rotated along a circle in an electric field generated by another point charge Q. The work done by the electric field on the rotating charge in one complete revolution is 

The electric field and the electric potential at a point are E and V, respectively.  

Electric potential decreases uniformly from 120 V to 80 V, as one moves on the x-axis from x = −1 cm to x = +1 cm. The electric field at the origin 

(a) must be equal to 20 Vcm⁻¹
(b) may be equal to 20 Vcm⁻¹
(c) may be greater than 20 Vcm⁻¹
(d) may be less than 20 Vcm⁻¹ 

Which of the following quantities does not depend on the choice of zero potential or zero potential energy?

The electric field in a region is directed outward and is proportional to the distance rfrom the origin. Taking the electric potential at the origin to be zero, 

Two resistors A and B have resistances R_A and R_B, respectively, and R_A < R_B. The resistivities of their materials are ρ_A and ρ_B.

A wire of length 1 m and radius 0.1 mm has a resistance of 100 Ω. Find the resistivity of the material.

A uniform wire of resistance 100 Ω is melted and recast as a wire whose length is double that of the original. What would be the resistance of the wire?

What length of a copper wire of cross-sectional area 0.01 mm² will be needed to prepare a resistance of 1 kΩ? Resistivity of copper = 1.7 × 10^–8 Ωm