# Electron energy derivation

Woopa
Homework Statement:
Derive the equation
Relevant Equations:
E=P^2/2m I am having trouble understanding this derivation and need some guidance.

1) I tried solving the algebra from the first equation to the second equation circled in red. Can someone please help with what algebra steps, I cannot solve to the circled solution.

2) What does Ee stand for? Is it Total energy of the electron?

3) Where did the value 5.49x10-4 come from? This does not appear to be the mass of the electron.

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2) Kinetic energy of the electron

3) it is the electron mass’ numerical value in the atomic mass unit u (which also the proton mass is given in). Units are important.

Mentor
Homework Statement:: Derive the equation
Relevant Equations:: E=P^2/2m

1) I tried solving the algebra from the first equation to the second equation circled in red. Can someone please help with what algebra steps, I cannot solve to the circled solution.
What did you try? Hint: $$\frac{A}{B} + \frac{A}{C} = A(\frac{1}{B} + \frac{1}{C})$$

Hint: Find a common denominator to express that sum of fractions as a single fraction.

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