An electron has a kinetic energy of 3.00 ev. find its wavelength. (b) what if? a photon has energy 3.00 ev. find its wavelength.

The wavelength of the electron from the given kinetic energy is .

The wavelength of the electron from the given photon energy is .

Momentum of the electron

The momentum of the electron is calculated as follows;

Wave of the electron

The wavelength of the electron is determined by using  De Broglie's equation.

Wavelength of the electron from the given photon energy

E = hf

Learn more about wavelength of photons here: link

(a) The electron kinetic energy is

which can be converted into Joule by keeping in mind that

So that we find


The kinetic energy of the electron is related to its momentum p by:

where m is the electron mass. Re-arranging the equation, we find


And now we can use De Broglie's relationship to find its wavelength:

where h is the Planck constant.

(b) By using the same procedure of part (a), we can convert the photon energy into Joules:


The energy of a photon is related to its frequency f by:

where h is the Planck constant. Re-arranging the equation, we find


And now we can use the relationship between frequency f, speed of light c and wavelength  of a photon, to find its wavelength:

Molybdeum(mo)orruthenium (ru)actually, elements with similar chemical properties as technetium would bemn, re, and bh. this is because elements in the same group/family (column) have similar chemical properties. elements in the same period (row) have the same number of energy levels (or shells).