Energy loss of an electron through Air?

[doanta]

Homework Statement

What is the energy loss in 3 mm of air (density = 1.20479E-03) of an electron with energy of 1.77MeV?

The Attempt at a Solution

I've found the Mass stopping power which is 1.696 MeV cm^2/g
and then linear stopping power of 2.04E^-3 MeV/cm

but from this point I'm stumped and unsure of what direction to take. Would anyone be able to offer any small hints to nudge me in the correct direction? Thank you

stopping power S= dE/dL

dE = energy loss
dL = path length

would I be over simplifying if...

I took the linear stopping power (2.04E^-3 MeV/cm * 0.3cm) to get the energy loss as 6.12E-4 MeV?

 

[mark726]

Hi there,

It looks like you're on the right track! To find the energy loss in 3 mm of air, you can multiply the linear stopping power by the thickness of the material. However, make sure to convert the thickness from centimeters to grams, since the linear stopping power is given in units of MeV/cm. This will give you the energy loss in MeV.

So, your final answer should be S * dL = (2.04E^-3 MeV/cm * 3 mm * 1 g/cm^3) = 6.12E-6 MeV. This is a very small amount of energy loss, which makes sense since air is a relatively low-density material.

I hope this helps! Let me know if you have any further questions.