Table of Contents

## What is the equation that relates the energy of a photon to its frequency?

E = h ν

The energy associated with a single photon is given by E = h ν , where E is the energy (SI units of J), h is Planck’s constant (h = 6.626 x 10–34 J s), and ν is the frequency of the radiation (SI units of s–1 or Hertz, Hz) (see figure below).

**How do you calculate the energy of a photon of electromagnetic radiation?**

h is Planck’s Constant, f is the frequency, c is the speed of light, and λ is the wavelength of the radiation.

- EXAMPLE 1. Calculate the energy of a photon of radiation whose frequency is 5.00×1014Hz .
- Solution 1. E=hf=6.626×10−34J⋅s ×5.00×1014s−1 =3.31×10−19J.
- EXAMPLE 2.
- Solution 2.

### What is the energy in joules and electron volts of a photon of 420 nm violet light?

KEe=hν–Φ=2.96eV–2.71eV=0.246eV. The energy of this 420-nm photon of violet light is a tiny fraction of a joule, and so it is no wonder that a single photon would be difficult for us to sense directly—humans are more attuned to energies on the order of joules.

**Which type of electromagnetic radiation is highest in energy?**

Gamma rays

Gamma rays have the highest energies and shortest wavelengths on the electromagnetic spectrum.

## How do you calculate eV frequency?

So 1 eV = (1.6 x 10^-19 coulombs)x(1 volt) = 1.6 x 10^-19 Joules. Now let’s calculate the frequency of the 1 eV photon. E = hf, so f = E/h. Hence, f = 1 eV/6.63 x 10-34 Joule-sec x (1.6 x 10-19 Joule / 1 eV) = 2.41 x 1014 sec-1 or 2.41 x 1014 Hz ( Hz means 1/sec).

**What is the energy of therapeutic electrons expressed in MeV?**

Whereas, the energy of therapeutic electrons is expressed in terms of MeV. In first case, this voltage is the maximum electric potential used by a linac to produce the photon beam. The beam has a spectrum of energies: the maximum energy is approximately equal to the beam’s maximum electric potential times the charge of the electron.

### What is the difference between eV and MeV?

A MeV is the Mega electron-volt, e.g. million times more than eV. One eV is defined as the energy, that an electron (or an other single-charged (q=1.6*10^-19 Coulombs) particle) gains when it undergoes a potential difference of 1 Volt. In the International units (SI units) 1eV corresponds to 1.6*10^-19 Joules.

**What does the unit MV mean in radiology?**

The unit MV (and for that matter kV) is supposedly strictly applied to x-ray generation although I understand you can see it being used in describing a radionuclides when their energy exceeds 1MeV. (Khan 1994) The MV designates a heterogeneous photon beam spectrum produced by an electron beam (of the same number MeV) striking a target.

## What is the difference between MeV and bremsstrahlung?

On the other hand, photons emitted from a breamsstrahlung device such as an X-ray tube or a linear accelerator has an energy spectrum with energies from 0 up to the energy of the electrons creating the bremsstrahlung. Photons emitted from a radioactive decay would properly be labeled MeV because they are mono-energetic.