Question

Light of wavelength 4000A0 falls on the surface of caesium metal. If the threshold wavelength of the metal is 6000A°, calculate the energy of the photoelectron.

Answer 1

Explanation:

1 eV

Work function is the minimum energy required by an electron to just escape from the metal surface as to overcome the restraining forces at the surface of metal.

According to Einstein's photoelectric equation the work function of metal is given by :

∴ϕ=

λ

hc

−KE

max

=

4000×10

−10

6.6×10

−34

×3×10

8

−2eV

=4.95×10

−19

−2eV

=

1.6×10

−19

495×10

−19

−2eV

=3eV−2eV=1eV

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