Question

What is the wavelength of a photon having energy of `1.257 times 10^-24` joules (Plancks constant is# 6.626 x 10^-34 joule seconds; the speed of light is 2.998 x 10^8 m/s)?

Answer 1

I got: `0.158m`

Explanation:

We use Einstein's Equation:
`E=hf`
where:
`E=`energy;
`f=`frequency;
`h=`Planck's constant.

And the relationship:

`c=lambdaf`
where:
`c=` speed of light;
`lambda=` wavelength.

from the first:
`f=E/h=(1.257xx10^-24)/(6.626xx10^-34)=1.897xx10^9Hz`
from the second:
`lambda=c/f=(2.998xx10^8)/(1.897xx10^9)=0.158m`