Answer:
Explanation:
The energy emitted by a single photon is given by:
where
h is the Planck constant
c is the speed of light
is the wavelength of the photon
For the photons emitted by the zinc atoms,
So the energy of a single photon emitted is
And since the number of atoms is
The total energy emitted will be
We can visualize the problem in another way, which is equivalent but easier to solve: let's imagine we hold one proton in the same place, and we move the other proton from a distance of 2.00×10−10 m to a distance of 3.00×10−15 m from the first proton. How much work is done?
The work done is equal to the electric potential energy gained by the proton:
where is the charge of the proton and
is the potential difference between the final position and the initial position of the proton. To calculate this
, we must calculate the electric potential generated by the proton at rest at the two points, using the formula:
where is the Coulomb constant and Q is the proton charge. Substituting the initial and final distance of the second proton, we find
Therefore, the work done is