Question

light with a wavelength of 400nm strikes the surface of metallic cesium in photo cell.and maximum kinetic energy of the electron enjected is 1.54×10^-19 J.calculate t
the work function of cesium and the longest wavelengthof light that is cappable of enjecting electrons from that metal ?​

Answer 1

Energy of incident photon is E=

λ(nm)1240V= 4001240 =3.1eV

And work function is W=2.5eV

So maximum energy of ejected electron will be, KE=E−W=3.1eV−2.5eV=0.6eV=0.6×1.6×10

−19

Joule

Maximum possible linear momentum will be p=

2

2mKE

= 22×9.1×10

−31Kg×0.96×10 −19 Joule=4.12×10−25

Kgm/s