Question

electromagnetic radiation having a wavelength 310 are subjected to a metal sheet

Answer 1

If an electromagnetic radiation having a wavelength of 310 angstrom is subjected to a metal sheet having a work function of 12.8 eV, what is the velocity of its photoelectrons with the maximum kinetic energy? ...

Answer 2

"Energy of photon of wavelength, Lambda=310x10^-10m is hc/ Lambda. Therefore ,E( photon)=(6.62x10^-34)(3x10^8)/(31x10^-9)=6.406x10^-18 J.

Work function, W= 12.8 eV= 12.6x1.6x10^-19J.=2.016x10^-18 J.

Now, maximum kinetic energy of photo electron, (1/2)mv( max)^2=E(photon)-W=6.406x10^-18 -2.016x10^-18 J=4.39x10^-18J. This makes it a vey important expression. It is related with the energy and the momentum.

Therefore,v( max)^2=(4.39x10^-18)(2)/(9.1x10^-31)=9.648x10^12 m^2/s^2.

Therefore, v( max)=3.106x10^6 m/s"