# Electron energy derivation

• Woopa
In summary, the conversation discusses a derivation and asks for help in understanding the steps. It also clarifies the meaning of certain symbols and questions the source of a specific value. The conversation ends with a hint for solving the problem.

#### 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.

1) Please show us your attempt.

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.

Woopa said:
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.

... or, just multiply by ##BC##.

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