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

Can a plane mirror ever form a real image?

A point source of light is placed in front of a plane mirror.

following Figure shows two rays A and B being reflected by a mirror and going as A' and B'. The mirror

The rays of different colours fail to converge at a point after going through a converging lens. This defect is called

Mark the correct options.

Which of the following (referred to a spherical mirror) do (does) not depend on whether the rays are paraxial or not?
(a) Pole
(b) Focus
(c) Radius of curvature
(d) Principal axis

A light ray falling at an angle of 45° with the surface of a clean slab of ice of thickness 1.00 m is refracted into it at an angle of 30°. Calculate the time taken by the light rays to cross the slab. Speed of light in vacuum = 3 × 10⁸ m s⁻¹.

A cylindrical vessel of diameter 12 cm contains 800π cm³ of water. A cylindrical glass piece of diameter 8.0 cm and height 8.0 cm is placed in the vessel. If the bottom of the vessel under the glass piece is seen by the paraxial rays (see figure), locate its image. The index of refraction of glass is 1.50 and that of water is 1.33.

A small object is placed at the centre of the bottom of a cylindrical vessel of radius 3 cm and height 4 cm filled completely with water. Consider the ray leaving the vessel through a corner. Suppose this ray and the ray along the axis of the vessel are used to trace the image. Find the apparent depth of the image and the ratio of real depth to the apparent depth under the assumptions taken. Refractive index of water = 1.33.

A light ray is incident at an angle of 45° with the normal to a √2 cm thick plate (μ = 2.0). Find the shift in the path of the light as it emerges out from the plate.

A light ray is incident normally on the face AB of a right-angled prism ABC (μ = 1.50) as shown in figure. What is the largest angle ϕ for which the light ray is totally reflected at the surface AC?

Find the maximum angle of refraction when a light ray is refracted from glass (μ = 1.50) to air.

Find the angle of deviation suffered by the light ray shown in figure. The refractive index μ = 1.5 for the prism material.

A light ray, going through a prism with the angle of prism 60°, is found to deviate by 30°. What limit on the refractive index can be put from these data?

For paraxial rays, show that the focal length of a spherical mirror is one-half of its radius of curvature.

Consider the diffraction pattern for a small pinhole. As the size of the hole is increased ______.

1. the size decreases.
2. the intensity increases.
3. the size increases.
4. the intensity decreases.

A polariod (I) is placed in front of a monochromatic source. Another polatiod (II) is placed in front of this polaroid (I) and rotated till no light passes. A third polaroid (III) is now placed in between (I) and (II). In this case, will light emerge from (II). Explain.

AC = CO = D, S₁C = S₂C = d << D

A small transparent slab containing material of µ = 1.5 is placed along AS₂ (Figure). What will be the distance from O of the principal maxima and of the first minima on either side of the principal maxima obtained in the absence of the glass slab?

Four identical monochromatic sources A, B, C, D as shown in the (Figure) produce waves of the same wavelength λ and are coherent. Two receiver R₁ and R₂ are at great but equal distances from B.

1. Which of the two receivers picks up the larger signal?
2. Which of the two receivers picks up the larger signal when B is turned off?
3. Which of the two receivers picks up the larger signal when D is turned off?
4. Which of the two receivers can distinguish which of the sources B or D has been turned off?

Draw the graph showing intensity distribution of fringes with phase angle due to diffraction through a single slit. What is the width of the central maximum in comparison to that of a secondary maximum?