28 The interference pattern is obtained with two coherent light sources of intensity ratio 4 In the min will be max interference pattern ratio max 1 4 3 3 8 9 29 Which voltmeter will give non zero reading at resonance 1 Only V 3 Both V and V3 V 1 30 A non conducting disc of radius R charged uniformly over one side with surface charge density rotate about its geometrical axis with an angular velocity The magnetic moment of the disc is COMGR 3 OMGR 2 B 2 1 9 4 5 4 R B D 2 Only V 4 Both V and V 3 4 MGR 31 The magnetic susceptibility of a magnetic material at 227 C is 0 00002 Then magnetic susceptibility of material at 727 C will be D 1 0 00002 2 0 00004 3 0 00001 4 0 00008 32 All straight wires are very long Both AB and CD are arcs of the same circle both sub tending right angles at the centre O Then the magnetic field at O is o 2 CONGR A 1 J 3 Ho 4xR 1 2TR 33 In a plane electromagnetic wave the electric field oscillates sinusoidly at a frequency of 2 x 1010 Hz and amplitude of 48 V m The frequency of oscillation of magnetic field will be 1 2 x 100 Hz 2 16 10 Hz 3 3 2 x 100 Hz 4 16 x 100 Hz 34 A charge Q is situated at the corner of the cube The electric flux through the cube will be o o 2 2 1 sin 3 4TR Hoi 4 x 1 2nR NIE 8 35 The capacity of a parallel plate capacitor depends on 1 The metal used to make the plate NIE 2 2 The thickness of the plates 3 The potential applied across the plates 4 The separation between the plates 36 A prism of refractive index u and refracting angle A is placed in the minimum deviation position If the angle of minimum deviation is A then the value of A in term of u is 2 sin 1 Spherical 3 Cylindrical Q 4 2 3 2 cos 4 cos 37 The magnifying power of an astronomical telescope for normal adjustment is 10 and the length of telescope is 110 cm The magnifying power of the telescope when image is formed at the least distance of distinct vision is 1 14 2 48 3 28 4 52 38 The condition of observing Fraunhalfer diffraction from a single slit is that the wavefront incident on the slit must be NIE 2 Elane 4 Elliptical