51. 52. Spherical aberration in a thin lens can be reduced by ---- A) Using a monochromatic light B) Using a circular annular mask over the lens C) Increasing the size of the lens D) Using a doublet combination Consider two sinusoidal waves with the same amplitude 'a'. According to the principle of superposition, the resultant amplitude 'A' is - if the phase difference between the two waves is equal to 0, 2, 4, 6 ---. ------- 53. 54. A) 2a B) 2a C) a2 D) 4a A plane intercepts at a, b/2, 3c in a simple cubic unit cell. The Miller indices of the plane will be A) (132) B) (261) C) (361) D) (123) A simple cubic lattice consists of eight identical spheres of radius R in close contact placed at the corners of the cube. What fraction of the total volume of the cube is actually occupied? A) 52.3% B) 75% C) 25.5% D) 90% 55. The shape of the orbital is determined by the A) Principal quantum number B) Spin quantum number C) Azimuthal quantum number D) Magnetic quantum number