Question

when monochromatic light of wavelength 5500x10^-10 shines on a metal , photoelectrons with maximum kinetic energy 1.02eV are emitted . if the wavelength of the incident light changes to 4800x10^-10 , the max kinetic energy of photoelectrons becomes 1.35eV . calculate the value of Planck constant based on information given , can somebody try solve this question and explain for me , i don't get it all . please.

Answer 1

this sum involves use of planks theorey and photoelectric effect

by planck's theorey
E=h*(frequency)

where E is the energy
h is planck's constant

frequency=c/wavelength

where c is speed of light
there is a minmum frequency(threshold frequency needed for ejection of an electron)
E0 gives the energy associared with it
E=E0+K.E
k.e is kinetic energy

so
E0=E-K.E===> 1
E0 is going to remain the same whatever the case is
find E1 and then E2 finding frequencies
in E=h*frequency ,leave h alone
use equation 1 and equate both equations and find h
be back when u have doubt in this....

Answer 2

hc/lemda1=work function+(maximum kinetic energy)1..(1)
hc/lemda2=work function+(maximum kinetic energy)2...(ii)
lemda1=5500*10^-10 m,(maximum kinetic energy)1=1.02ev
lembda2=4800x10^-10m,(maximum kinetic energy)2=1.35ev
c=3*10^8m/sec
using this two equation ,find the value 0f h.