NEET UG Physics Dual Nature of Matter MCQs

73. Photo senstive surface is incident by light having frequecy 3 times its threshold frequency. In this condition, if frequency of light is made half and intensity of light is made doubel, magnitude of photo electric current becoms____
(A) Fourth (B) double (C) half (D) zero

74. If ratio of threshold frequencies of two metals is 1 : 3, ratio of their work functions is ____
(A) 1 : 3 (B) 3 : 1 (C) 4 : 16 (D) 16 : 4

75. It work function of Na and Fe are 2.5 eV and 5eV respectively ratio of their threshold frequencies _______
(A) 2 :1 (B) 1 : 2 (C) 125 : 1 (D) 1 : 1

76. If electrion is accelerated under the effect of 200V p.d., its kinetic energy = ______
(A) 1.6 × 10^-17 J (B) 23 × 10^-17 J (C) 4.8 × 10^-17 J (D) 6.4 × 10^-10 J

77. In quantum mechaincs, a particle _____
(A) can be regarded as group of harmonic waves.
(B) can be regarded as a single wave of definite wavelength only
(C) Can be regarded as only a pair of two harmonic waves
(D) is a point-like object with mass.