Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

Download the PDF Sample Papers Free for off line practice and view the Solutions online.

ISC Class 12 Physics Solved Question Paper 2008

Short Answer Type

31. Draw a labelled diagram of Michelson’s method to determine the speed of light in air.

445 Views

32. What is the essential difference between polarised light and unpolarized light ? Find Brewster’s angle for water having refractive index n = 1.33.

In polarised light, the direction of propagation of vibrations is perpendicular to the direction of motion of light.

In unpolarised light, vibrations are unidirectional in a plane perpendicular to the direction of motion of light.

According to Brewster’s Law,

μ = tan i_p

i_p = tan^-11.33

i_p = 53.06°

Brewster angle is 53.06°.

510 Views

33.

When two thin lenses of focal lengths f₁ and f₂ are kept in contact, prove that their combined focal length 'f' is given by

734 Views

34. Draw a labelled Ray diagram of an image of a distant object formed by a refracting astronomical telescope in normal adjustment. Write (do not derive) an expression for its magnifying power.

452 Views

35. In a compound microscope consisting of two convex lenses of focal lengths 1.5 cm and 10 cm, the object is 2 cm from the objective and the final image is formed at the least distance of distinct vision (C = 25 cm). Find the distance of separation of the two lenses.

617 Views

36. A parallel beam of monochromatic light of wavelength 500 nm is incident normally on a rectangular slit. The angular width of the central bright fringe of Fraunhofer diffraction is found to be 60°. Find the width of the slit in metre.

528 Views

37.

An electron beam passes through crossed electric and magnetic fields of 3.4 x 10⁴ Vm^-1 and 2 x 10^-3 Wb mr^-2 respectively. If the path of the beam remains undeviated, calculate the speed of the electrons.

If the electric field is removed, what will be the radius of the circular path described by the electrons ?

364 Views