51. The given graph represents V − I characteristic for a semiconductor device. Which of the following statement is correct?

50. The barrier potential of a p − n junction depends on:

(A) type of semi conductor material

(B) amount of doping

(C) temperature

Which one of the following is correct?

30. A beam of light of λ = 600 nm from a dis- tant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between first dark fringes on either side of the central bright fringe is:

14. In the Young’s double-slit experiment, the intensity of light at a point on the screen where the path difference is λ is K, ( λ being the wave length of light used). The intensity at a point where the path difference is λ/4, will be :

73. If the focal length of objective lens is increased then magnifying power of :

59. The angle of a prism is ’ A ’. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2 A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive index μ, of the prism is :

Two thin dielectric slabs of dielectric constants K1 and K2 ( K1 < K2) are inserted between plates of a parallel plate capacitor, as shown in the figure. The variation of electric field ’E’ between the plates with distance ’d’ as measured from plate P is correctly shown by ?

In a region, the potential is represented by V (x, y, z) = 6x − 8xy − 8y + 6yz, where V is in volts and x, y, z are in metres. The electric force experienced by a charge of 2 coulomb situated at point (1, 1, 1) is ?

A conducting sphere of radius R is given a charge Q. The electric potential and the electric field at the centre of the sphere respectively are ?