# Stopping Potential Question

## Homework Statement

Electrons are accelerated through a potential V and then they are suddenly stopped and emit photons. Derive the minimal value that the potential should have in order to produce some X-Ray photons of wavelength 10-10m.

E=hc/λ
V=(h/e)(f-f0)

## The Attempt at a Solution

I used E=hc/λ to find the energy of the X ray photons. I found E= 1.989x10-15 = 12431.25 eV

Not sure if I needed to do this or what to do next. All help is appreciated. Thank you.

## Answers and Replies

gneill
Mentor
Hi DarkMatter5, Welcome to Physics Forums!

## Homework Statement

Electrons are accelerated through a potential V and then they are suddenly stopped and emit photons. Derive the minimal value that the potential should have in order to produce some X-Ray photons of wavelength 10-10m.

E=hc/λ
V=(h/e)(f-f0)

## The Attempt at a Solution

I used E=hc/λ to find the energy of the X ray photons. I found E= 1.989x10-15 = 12431.25 eV

Not sure if I needed to do this or what to do next. All help is appreciated. Thank you.
You have found the energy, and cleverly expressed it in electron volts. What electric potential difference (Volts) should the electron be accelerated through in order to achieve that energy?

By the way, you might want to round your result to suit the given significant figures.

• DarkMatter5
Hi DarkMatter5, Welcome to Physics Forums!

You have found the energy, and cleverly expressed it in electron volts. What electric potential difference (Volts) should the electron be accelerated through in order to achieve that energy?

By the way, you might want to round your result to suit the given significant figures.

I guess it would be 12431.25 V? And is it to 1 sig fig? so 1 x 104 V?

gneill
Mentor
Yup.

• DarkMatter5
Yup.
Thank you very much!