## Converting Between keV and Joules

Remi Lathrop 1G
Posts: 51
Joined: Fri Sep 29, 2017 7:07 am

### Converting Between keV and Joules

When I was working on problem 23 from chapter 1, the question states that the gamma ray photons emitted have a energy of 140.511 and asked for the wavelength of the gamma rays. When I checked the solution manual it showed that before plugging the given value into any equation you must multiply the given 140.511 x 10^3 eV by 1.6022 x 10^-19 J/eV.

I understand that we want our energy value in J, but why did they multiply by 1.6022 x 10^-19 ? And maybe more fundamentally what is a "keV"?

AnuPanneerselvam1H
Posts: 52
Joined: Fri Sep 29, 2017 7:07 am

### Re: Converting Between keV and Joules

1.6022 x 10^-19 J/eV is a ratio that is used to convert between the two units since most equations use Energy in Joules. Also I think k stands for kilo in this case. Therefore it would be 1.6022 x 10^-16J/ keV

Jordan Foster
Posts: 22
Joined: Fri Sep 29, 2017 7:06 am

### Re: Converting Between keV and Joules

Dr. Lavelle also mentioned that we do not need to memorize the conversions for units like KeW to J. We will be given conversion equations on a sheet of constants and equations so as long as you know how to use and manipulate the equations, you will be fine.

DAllaf
Posts: 20
Joined: Fri Sep 29, 2017 7:04 am

### Re: Converting Between keV and Joules

HI Remi,

In lecture Dr. Lavelle mentioned how we do not need to memorize unit conversions like that, because we would be provided a sheet full of equations and conversation during exams. So just try to practice problem solving and making the equations work together and you'll be fine.

Hope this helps