Question

Calculate the velocity of electron ejected from a platinum surface when radiation of 200 nw falls on it . The work function of platinum is 5ev. (1ev = 1.6*10-19)

Answer 1

Answer on Question #43955, Physics, Atomic Physics

Calculate the velocity of electron ejected from a platinum surface when radiation of $\lambda=200$ nw falls on it . The work function of platinum is $A=5$ eV = $8\cdot 10^{-19}$ J(1ev = 1.6*10-19 J).

Solution

Velocity can be found from energy conservation law

$hc/\lambda=A+mv^{2}/2$

$v=\sqrt{2(hc/\lambda-A)/m}=\sqrt{2(6.3\cdot 10^{-34}\cdot 3\cdot 10^{8}/(200\cdot 10^{-9})-8\cdot 10^{-19})/(9.1\cdot 10^{-31})}$

$\approx 0.4\cdot 10^{6}\,m/s$