RSMSSB Lab Assistant exam 2019 Answer Key – English

121 The effective resistance between points A and B in given circuit is –

(A) 5Ω
(B) 10Ω
(C) 40Ω
(D) 50Ω

122 A potentiometer wire is supplied a constant voltage of 3 V. A cell of emf 1.08 V is balanced by the wirthe voltag drop across 216 cm of the wire. The total length of the potentiometer wire is (A) 200 cm
(B) 400 cm
(C) 600 cm
(D) 800 cm

123 Can We use copper wire as a potentiometer wire ? Choose the correct option
(A) No, because its resistivity is very high.
(B) Yes, because it has small resistivity.
(C) No, because it has small resistivity and also its temperature coef very large.
(D) Yes, because it has very large temperature coefficient of resistance.

124 Potentiometer measures the potential difference more accurately than a voltmeter, because:
(A) It has a wire of low resistance.
(B) It has a wire of high resistance.
(C) It draws a heavy current from external circuit.
(D) It does not draw current from external circuit.

125 In Young’s double slit experiment, the monochromatic source of yellow light is replaced by
that of a red one light then fringe width will ________ .
(A) increase
(B) decrease
(C) remain unchanged
(D) disappear

126 In a Young’s double slit experiment the slit separation is 1 mm and the a monochromatic light of wavelength 500 nm, the distance of 3rd minimam the central maxima is –
(A) 0.50 nam
(B) 1.25 mm
(C) 1.50 ml
(D) 1.75 mm

127 Brewster’s law is –
(A) i_{p= 90°
(B) μ= tanip
© ip-r = tan μ
(D) ip = tan μ
(where μ = refractive index and ip = polarising angle)}

128 In Fraunhofer diffraction at single slit if slit width is decreased, the adjacent minima
(A) come closer
(B) move apart
(C) remain at the inital positions
(D) come closer initially and then inow

129 The longest wavelength in Balmer series of hydrogen spectrum will be –
(A) 6557Å
(B) 1216 Å
(C) 4800 Å
(D) 5600 Å

130 When hydrogen atom is in its first excited state, its radius compared to that of grour is –
(A) same
(B) half
(C) twice
(D) four times

131 The energy required by a hydrogen atom in ground state, to move to its first excit is –
(A) 13.6 eV
(B) 3.4 eV
(C) 10.2 eV
(D) 12.2 eV

132 The binding energy per nucleon for a deuterium nucleus is 1.115 MeV. Mass defect for this nucleus is about-
(A) 2.23 μ
(B) 0.0024 μ
(C) 0.027 μ
(D) 0.0012 μ

133 The electron emitted in beta radiation originates from –
(A) inner orbits of atoms.
(B) free electrons existing in nuclei.
(C) in decay of a neutron in a nuclei.
(D) photon escaping from the nucleus.

134 When7/4 Li bombarded with a certain particle, two alpha particle are produced.
(A) neutron
(B) proton
(C) alpha particle
(D) deuteron

135 In the half wave rectifier circuit operating from 50 Hz main frequency, the fundamental frequency in the ripple would be –
(A) 25 Hz
(B) 70.7 Hz
(C) 100 Hz
(D) 50 Hz

136 At absolute zero temperature, intrinsic germanium and intrinsic silicon are –
(A) Ideal Conductor
(B) Good Semiconductor
(C) Ideal Insulator
(D) Conductors

137 The logic gate represented in the following figure is –

(A) OR Gate
(B) NOT Gate
(C) NAND Gate
(D) XOR Gate

138 The doors are provided with handles near the outer edges Hall maximum torque on the door to open it easily.
(A) to exert maximum torque on the door to open it easily.
(B) to exert minimum torque on the door to open it easily.
(C) because position of handle does not matter and is convenient to fix at the outer easily.
(D) because while opening the door fingers are not hurt by hinges.

139 Consider a two particle system with particle masses m ₁ and ₂ if the frist particle towards the centre of mass through a distance d, by what distance should second particle be moved, to keep the centre of mass at the same position?

140 A circular disc of radius 05 m and mass 25 kg is rotating about its own axis with of 120 revolution/min. The moment of inertia of the disc is –
(A) 1.550 kg m1
(B) 3.125 kg m1
(C) 4.125 kg m1
(D) 6.250 kg m1

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