what is the mass equivalence ( in kg) of a 35 KeV x-ray?

Question

Please don't bother if you are unable or unwilling to show a calculation.

Answer 1

the xray has to have some duration to be equivalent to mass.
E = mc2
35,000 eV = m * (300,000 km/s)^2
m = 35,000 eV / 9x10^10 km2/s2
m = 3.89 x 10^-7 ev sec^2 km^-22
from this site
http://www.knowledgedoor.com/1/Unit_Conversion/Convert_to_New_Units.aspx
we learn
The units are inconsistent. The dimensions of the units in the "From" entry do not match the dimensions of the units in the "To" entry.

The "From" entry was interpreted as follows:

10 electron-volt seconds

which has dimensions of

length^2 × mass × time^-1



The "To" entry was interpreted as follows:
kilogram
which has dimensions of
mass

Answer 2

First, you need to convert the energy of the x-ray from keV to Joules

Step 1 Convert keV into eV by multiplying it by 10^3
(35 keV) (1 X 10^3 eV/1keV)

Step 2 Convert eV into Joules by dividing by Joule equiv = 1J= 6.24 x 10^18 eV
(35000 eV)(1 J/6.24 x 10^18 eV)

Now we have the value of 35 keV is = 5.6 x 10^-15 J

Now, use E=mc^2 where this value = E

5.6 x 10^-15J = m(3 x 10^8)^2
You have to square the speed of light

Now divide both sides by speed of light squared (3 x 10^8 m/s)
5.6 x 10^-15 = m(9 x 10^16 m^2/s^2)

m=6.2 x 10^-32 Js^2/m^2

reduce
m = 6.2 x 10^-32 kg