The de- Broglie wavelength of an electron moving with a velocity `1.5xx10^(8) ms^(-1)` is equla to the wavelenght of a photon. The ratio of the kinetic energy of the electron to that of the energy of photon is

Explanation

Speed of photon (c ) `=3xx10^(8)ms^(-1)`. Let `lamda` be the wavelength of the photon. The de Broglie wavlength of the electron is `(h)/(mv)`.
Given `lamda=(h)/(mv)` Now
`(KE of Phot on)/(KE of el ectron)=(hf)/((1)/(2)mv^2)=(2hc)/(mv^2lamda)=(2c)/(v)`
`=(2xx3xx10^(8))/(1.5xx10^(8))=4`