Answer to Question #290155 in Quantum Mechanics for Ada

Question

Calculate the maximum energy and the speed

of the emitted electrons when sodium is

illuminated by a radiation of wavelength

150nm. What is the least frequency of radiation

(threshold frequency) for which electrons are

emitted?

(Take work function of sodium as 2.0eV).

Given that me= 9.109 x 10-31kg,

mn= 1.675 x 10-27kg, and

mp= 1.672 x 10-27kg

Answer 1

$h\frac c\lambda=A+E,$

$E=h\frac c\lambda-A=6.3~eV,$

$v=\sqrt{\frac {2E}m}=1.49\cdot 10^6~\frac ms .$

$\nu_{min}=\frac Ah=482.7~GHz.$