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Electrical engineering material miscellaneous

Electrical Engineering materials

  1. If the frequency of light falling on a metal plate is doubled, the kinetic energy of emitted electrons will be:
    1. Exactly double
    2. Sightly more than double
    3. Slightly less than double
    4. Four times
Correct Option: C

Kinetic energy is given by

K. E. =
1
mv2 = hv – hν0 = hν – φ0
2

where, hν0 = φ0 = work function i.e. minimum photonic energy to liberate electron from metallic bonding.
ν = falling frequency
Thus,
(K.E.)2
=
2hν – φ0
(K.E.)1hν – φ0

from above relation, we can say that if the frequency of light falling on a metal plate is doubled, the kinetic energy of the emitted electrons will be slightly less than double.



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