Science (English Medium) कक्षा १२ - CBSE Important Questions

Two monochromatic rays of light are incident normally on the face AB of an isosceles right-angled prism ABC. The refractive indices of the glass prism for the two rays '1' and '2' are respectively 1.35 and 1.45. Trace the path of these rays after entering the prism.

Using the phenomenon of polarisation, show how the transverse nature of light can be demonstrated.

Two polaroids P₁ and P₂ are placed with their pass axes perpendicular to each other. An unpolarised light of intensity I₀ is incident on P₁. A third polaroid P₃ is kept in between P₁ and P₂ such that its pass axis makes an angle of 30° with that of P₁. Determine the intensity of light transmitted through P₁, P₂ and P₃

Show, via a suitable diagram, how unpolarised light can be polarised by reflection.

Monochromatic light of wavelength 589 nm is incident from air on a water surface. What are the wavelength, frequency and speed of (a) reflected and (b) refracted light? Refractive index of water is 1.33.

Consider a plane wave front incident on a thin convex lens. Draw a proper diagram to show how the incident wave front traverses through the lens and after refraction focusses on the focal point of the lens, giving the shape of the emergent wave front.

Draw a graph showing the variation of intensity (I) of polarised light transmitted by an analyzer with the angle (θ) between polariser and analyzer.

What is the value of refractive index of a medium of polarising angle 60°?

Find the intensity at a point on a screen in Young's double slit experiment where the interfering waves have a path difference of (i) λ/6, and (ii) λ/2. 

Draw the intensity distribution for the fringes produced in interference ?

Draw the intensity distribution for the diffraction bands produced due to single slit ?

Distinguish between polarized and unpolarized light. Does the intensity of polarized light emitted by a polaroid depend on its orientation? Explain briefly.
The vibration in a beam of polarized light make an angle of 60° with the axis of the polaroid sheet. What percentage of light is transmitted through the sheet?

State the essential conditions for diffraction of light ?

(i) State the essential conditions for diffraction of light.
(ii) Explain diffraction of light due to a narrow single slit and the formation of pattern of fringes on the screen.
(iii) Find the relation for width of central maximum in terms of wavelength 'λ', width of slit 'a', and separation between slit and screen 'D'.
(iv) If the width of the slit is made double the original width, how does it affect the size and intensity of the central band?

Draw a labelled schematic ray diagram of astronomical telescope in normal adjustment.

Which two aberrations do objectives of refracting telescope suffer from? How are these overcome in reflecting telescope?

How does the resolving power of a telescope change on increasing the aperture of the objective lens? Justify your answer.

How does the refractive index of a transparent medium depend on the wavelength of incident light used ?

Why cannot two independent monochromatic sources produce sustained interference pattern?
Deduce, with the help of Young's arrangement to produce interference pattern, an expression for the fringe width.

Monochromatic light of frequency 5.0 × 10¹⁴ Hz is produced by a laser. The power emitted is 3.0 × 10^–3 W. Estimate the number of photons emitted per second on an average by the source ?