Q. The maximum kinetic energy of the photoelectrons is found to be $6.63 \times 10^{- 19}$ J. When the metal is irradiated with a radiation of frequency $2 \times 10^{15}$ Hz, the threshold frequency of the metal is about
A) $2 \times 10^{15}{\ s}^{- 1}$
B) 1$\times 10^{15}{\ s}^{- 1}$
C) 2.5$\times 10^{15}{\ s}^{- 1}$
D) 4$\times 10^{15}{\ s}^{- 1}$
Explanation
(b)
Kinetic energy $= h(v - v_{0})$
KE $= hv - hv_{0}$
$v_{0} = v - \frac{KE}{h} = 2 \times 10^{15} - \frac{6.63 \times 10^{- 19}}{6.63 \times 10^{- 34}}$
$= 1 \times 10^{15}s^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.