Finding the kinetic energy of an electron

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Homework Statement



This is a basic photoelectric type question.

What wavelength of light is necessary to produce photo-electrons of speed 2 * 10^6 m/s with a magnesium target?

Homework Equations



KE = pf - phi

phi = 3.7 eV
h = 6.63 * 10 ^-34

The Attempt at a Solution



I don't know how to find the energy of an electron from the velocity. Once I have that I think I can figure it out
 
Last edited:
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I think I figured it out! E = .5 * m * v^2
 
Your equations are right =]
 

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Hi, I had an exam and I completely messed up a problem. Especially one part which was necessary for the rest of the problem. Basically, I have a wormhole metric: $$(ds)^2 = -(dt)^2 + (dr)^2 + (r^2 + b^2)( (d\theta)^2 + sin^2 \theta (d\phi)^2 )$$ Where ##b=1## with an orbit only in the equatorial plane. We also know from the question that the orbit must satisfy this relationship: $$\varepsilon = \frac{1}{2} (\frac{dr}{d\tau})^2 + V_{eff}(r)$$ Ultimately, I was tasked to find the initial...
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