OnlineCBT
Physics · PYQ NEET UG 2018
हिन्दीWhen the light of frequency \( 2 u_0 \) (where \( u_0 \) is threshold frequency), is incident on a metal plate, then the maximum velocity of electrons emitted is \( v_1 \). When the frequency of the incident radiation is increased to \( 5 u_0 \), the maximum velocity of electrons emitted from the same plate is \( v_2 \). The ratio of \( v_1 \) to \( v_2 \) is
Correct answer · Option 1
1 : 2
Explanation
Using Einstein's photoelectric equation \( \frac{1}{2}mv^2 = h\nu - h\nu_0 \). For \( 2\nu_0 \), \( \frac{1}{2}mv_1^2 = h(2\nu_0 - \nu_0) = h\nu_0 \). For \( 5\nu_0 \), \( \frac{1}{2}mv_2^2 = h(5\nu_0 - \nu_0) = 4h\nu_0 \). Taking the ratio, \( \frac{v_1}{v_2} = \sqrt{\frac{1}{4}} = \frac{1}{2} \).
