List of top Physics Questions on Ray optics and optical instruments asked in UP Board XII

Derive the formula \(\dfrac{n}{v}-\dfrac{1}{u}=\dfrac{n-1}{R}\) due to refraction of light on a spherical surface.
OR
Draw a circuit diagram of p-n junction full wave rectifier and describe its working. Also, give the graphical representation of input and output current.
Option 1: Write the 'lens maker' formula for a thin lens. The refractive index of the material of a thin lens is \( n \) and its focal length is \( f \). The lens is placed in a medium of refractive index \( n \). Find the focal length of the lens in the medium.
OR
Option 2: What is the difference between unpolarized and polarized light? Two polaroids A and B are placed such that light polarized by A cannot pass through B. Can some light be obtained by using a third polaroid?
An object is placed between centre of curvature and infinity in front of a concave mirror. Draw ray diagram for image.
Convex lens of focal length \(f_1\) is placed in contact with a concave lens of focal length \(f_2\). For \(f_1 > f_2\) combination will behave:
Derive the formula for the focal length of a thin lens.
OR
Explain the difference between diffraction and interference of light waves. Write down the formula for the fringe width in Young's double slit experiment. What will be the effect on the fringe width, when the separation between the slits is made one third and the distance between the slits and the screen is doubled? What will be the effect on the fringe width if the whole experiment is placed in water?

A rectangular glass slab ABCD of refractive index \(n_1\) is placed in a liquid of refractive index \(n_2\) (\(n_1 > n_2\)). A ray of light is incident at the surface AB of the slab as shown in the figure. Find out the maximum value of angle \(\alpha\), so that the ray comes out only from the other surface CD.
What is meant by the optical center of a lens?
In which of the following spherical mirrors is the magnification of the image always less than 1?
Show the position of focus (f) in ray diagram for convex mirror. At what distance from a convex mirror of focal length 2.0 m should a boy stand so that his image has a height equal to half the original height?
OR
What is wavefront? Explain the refraction of waves with the help of Huygens' principle.
Explain total internal reflection. Discuss the working of an optical fibre.
Draw the ray diagram of a compound microscope. Find the expression for its magnifying power.
Draw (i – δ) curve for a triangular prism and show the angle of minimum deviation.
By drawing ray-diagram, explain the formation of image by a compound microscope. Establish the formula for its magnifying power.
OR
What is meant by binding energy of nucleus? Draw the graph of binding energy per nucleon with respect to the mass number. Discuss fission and fusion reactions with the help of this curve.
An equiconcave lens of crown glass has to be formed. What should be the radii of the surfaces of the lens so that the power of the lens is \(-2.5\,\text{D}\)? The refractive index of crown glass is \(1.65\).
A convex lens of glass of focal length 15 cm is immersed in carbon disulphide. In this situation what will be the focal length and the nature of the lens? The refractive indices of glass and carbon disulphide (relative to air) are 3/2 and 5/3 respectively.
What will be the focal length of a combination of a convex and a concave lens of the same focal length (placed in contact)?
When a convex lens is dipped in water, its focal length and nature become:
The focal length of a glass \((n_g = 3/2)\) plano-convex lens in air is 10 cm. What will be the focal length and its nature when it is immersed in carbon disulphide \((n_c = 5/3)\)?
The distance between any two sources of light is 24 cm. Determine where a convergent lens of focal length 9 cm be placed so that the image of both sources be formed at one point.
In which the power of a lens will be large, in air or water?
If the critical angle in a medium is \( \alpha \), then for total internal reflection the angle of incidence \( \beta \) should be:
Reflecting telescopes are supposed to be better than refracting telescopes. Why? Draw the ray diagram for image formation by a refracting telescope. Final image is formed at infinity.
OR
What is the meaning of polarisation of light? Whether sound waves are also polarized? Explain polarization of light by refraction.
A convex and a concave lens are placed in contact. The focal lengths \( (F) \) of both are the same. The combination will behave: