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## Homework Statement

The X-ray intensity distribution function for an X-ray lamp is

given on the figure. What is the maximum velocity of the electrons? What is the potential difference under which the lamp is operating? Figure: http://imgur.com/01kCBc8

## Homework Equations

Kmax = 0.5m(vmax)^2

Kmax = hf - work function

λ = c/f

c = speed of light = 3 x 10^8 m/s

Peak wavelength (from the figure) = 3.5 x 10^-9 m

h = Planck's constant = 6.63 x 10^-34

m = mass of electron = 9.11 x 10^-31

## The Attempt at a Solution

Doubt I'm starting at the right place.

0.5mv^2 = hf (work function??)

0.5mv^2 = h(c/λ)

v = sqrt [2h(c/λ)/m]

v = 1.1 x 10^7 m/s

Given answer is 1.5 x 10^7 m/s

As for the potential difference, I have no idea how to calculate it.

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