# Compton effect question.

## Homework Statement

If x ray with a weavelength of 4.5*10^-12m are used in a Compton effect experiment and are scattered at an anlge of 53.0 degree, the wavelength of the scattered radiation is?

ANS: 5.47*10^-12

## The Attempt at a Solution

The only thing i could think of was Δλ=h/mc*(1-cosθ)
which doesnt work seeing as how the xray didnt impact anything, i even tried it as if it impaced an electron using the mass of the electron. What formula or concept am i missing?

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SammyS
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## Homework Statement

If x ray with a wavelength of 4.5*10^-12m are used in a Compton effect experiment and are scattered at an anlge of 53.0 degree, the wavelength of the scattered radiation is?

ANS: 5.47*10^-12

## The Attempt at a Solution

The only thing i could think of was Δλ=h/mc*(1-cosθ)
which doesn't work seeing as how the x-ray didn't impact anything, i even tried it as if it impacted an electron using the mass of the electron. What formula or concept am i missing?
In Compton scattering, the x-rays are usually scattered by electrons.

With that, I get the given answer.

Last edited:
rude man
Homework Helper
Gold Member

## Homework Statement

If x ray with a weavelength of 4.5*10^-12m are used in a Compton effect experiment and are scattered at an anlge of 53.0 degree, the wavelength of the scattered radiation is?

ANS: 5.47*10^-12

## The Attempt at a Solution

The only thing i could think of was Δλ=h/mc*(1-cosθ)
which doesnt work seeing as how the xray didnt impact anything, i even tried it as if it impaced an electron using the mass of the electron. What formula or concept am i missing?
For m did you use the rest mass of the electron? 'Cause the formula is correct.

I did

6.63*10^-34/ 9.11*10^31 * 3*10^8 * (1-cos53)= 9.65959164*10^-13

Then ANS - 4.5*10^-12 which yields 3.53*10^-12.

what did i do wrong?

SammyS
Staff Emeritus
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I did

6.63*10^-34/ 9.11*10^31 * 3*10^8 * (1-cos53)= 9.65959164*10^-13

Then ANS - 4.5*10^-12 which yields 3.53*10^-12.

what did i do wrong?
How about ANS + 4.5*10^-12 ?

How about ANS + 4.5*10^-12 ?
oh, how come its plus isnt Δλ= λi-λf, or is it plus? isnt the change in something usually subtract?

SammyS
Staff Emeritus