To explain the nature of radiation, James Clark Maxwell in 1864 put forward .Electromagnetic wave theory.. This theory could explain the phenomena of interference and diffraction but could not explain phenomena of black body radiation and photoelectric effect. Also, after the advent of electromagnetic wave theory, Rutherford.s model of atom suffered a serious drawback. To explain the phenomena of black body radiation and photoelectric effect, Max planck in 1900 put forward Planck.s quantum theory. BAsed on this theory, Neils Bohr in 1913 put forward Bohr.s model of atom which could overcome the drawback of Rutherford.s model and also explain the line spectral elements, especially the line spectra of hydrogen and hydrogen-like particles.
Kinetic energy of the electron ejected when yellow light of frequency `5.2 xx 10^(14) s^(-1)` falls on the surface of potassium metal (threshold frequency `= 5 xx 10^(14) s^(-1)`) is

Options

A. `1.325xx10^(-13)` J
B. `1.325xx10^(-20)` J
C. `1.325xx10^(-20)` J
D. `1.325xx10^(-34) J`

Answer

B

Explanation

`K.E. = hv - hv_0 = h(v-v_0)`
`=6.625 xx 10^(-34) Js - (5.2- 5.0)xx 10^(14) S^(-1)`
`= 1.325xx10^(-20)` J.