71. The value of energy quantum for radiation of any frequency is proportional to :
A. the frequency
B. the reciprocal of the energy
C. the square of the frequency
D. the square root of the frequency

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72. The emission of electrons from a metal plate exposed to light depends on the :
A. intensity of the light
B. frequency of light
C. both (a) and (b)
D. neither (a) nor (b)

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73. Assuming n as the frequency of radiation, no as the threshold frequency and k as a constant, the energy of the photo-electrons (E) is related as
A. E = k (n - no)
B. E = k (n + no)
C. E = k (a x no)
D. E = (n. + no)

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74. Which one of the following can travel through empty space :
A. sound waves
B. water waves
C. electromagnetic waves
D. spring waves

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75. 'A time varying magnetic field produces an electric field'. This phenomenon is known as
A. Newton's law
B. Kirchoff law
C. Ampere Maxwell law
D. Faraday's law

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76. 'A time varrying electric field produces a magnetic field.' This phenemenon is called:
A. Hertz's law
B. Ampere Maxwell's law
C. Faraday's law
D. Kirchoffs law

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77. The reflection of solar energy is characterised by the water content in the leaf, in the reflective optical infrared :
A. visible (0.4 ? 0.7 gm) region
B. near-IR (0.7 ? 1.3 gm) region
C. short wave-IR (1.3 ?2.7 gm) region
D. None of these

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