The terminology of different parts of the electromagnetic spectrum is given in the text. Use the formula $E=h v$ (for the energy of a quantum of radiation: photon) and obtain the photon energy in units of eV for different parts of the electromagnetic spectrum. In what way are the different scales of photon energies that you obtain related to the sources of electromagnetic radiation?
The terminology of different parts of the electromagnetic spectrum is given in the text. Use the formula $E=h v$ (for the energy of a quantum of radiation: photon) and obtain the photon energy in units of eV for different parts of the electromagnetic spectrum. In what way are the different scales of photon energies that you obtain related to the sources of electromagnetic radiation?

The energy of a photon is represented by the expression,

$\mathrm{E}=\mathrm{hv}=\frac{h c}{\lambda}$

Where,

$\mathrm{h}$ is the planck’s constant with a value of$6.6 \times 10^{-34} J_{S}$

$\mathrm{c}$ is the speed of light with a value of $3 \times 10^{8} \mathrm{~m} / \mathrm{s}$

If the energy is in Joule and the wavelength $\lambda$ is in metre, then by dividing $E$ by $1.6 \times 10^{-19}$ will convert the energy into $\mathrm{eV}$.

$E=\frac{h c}{\lambda \times 1.6 \times 10^{-19}} e V$

a) Because the wavelength of gamma rays runs from $10^{-10}$ to $10^{-14} \mathrm{~m}$, the photon energy can be computed as follows:

$E=\frac{6.62 \times 10^{-34} \times 3 \times 10^{8}}{10^{-10} \times 1.6 \times 10^{-19}}=12.4 \times 10^{3} \approx 10^{4} \mathrm{eV}$

So,

$\lambda=10^{-10} \mathrm{~m}$, energy $=10^{4} \mathrm{eV}$

$\lambda=10^{-14} \mathrm{~m}$, energy $=10^{8} \mathrm{eV}$

The range for the energy of Gamma rays is $10^{4}$ to $10^{8} \mathrm{eV}$.

b) The wavelength for $X$-rays ranges between $10^{-8} \mathrm{~m}$ to $10^{-13} \mathrm{~m}$

For $\lambda=10^{-8}$,

Energy will be $=\frac{6.62 \times 10^{-34} \times 3 \times 10^{8}}{10^{-8} \times 1.6 \times 10^{-19}}=124 \approx 10^{2} \mathrm{eV}$

For $\lambda=10^{-13} \mathrm{~m}$, energy $=10^{7} \mathrm{eV}$

c) For ultraviolet radiation, the wavelength ranges from $4 \times 10^{-7} \mathrm{~m}$ to $6 \times 10^{-7} \mathrm{~m}$.

For $4 \times 10^{-7} \mathrm{~m}$,

Energy will be $=\frac{6.62 \times 10^{-34} \times 3 \times 10^{8}}{4 \times 10^{-7} \times 1.6 \times 10^{-19}}=3.1 \approx 10^{10} \mathrm{eV}$

For $6 \times 10^{-7} \mathrm{~m}$, the energy is equal to $10^{3} \mathrm{eV}$.

The energy of the ultraviolet radiation has a variation between $10^{10}$ to $10^{3} \mathrm{eV}$.

d) The wavelength ranges from $4 \times 10^{-7} \mathrm{~m}$ to $7 \times 10^{-7} \mathrm{~m}$ for visible light.

The energy is the same as above for $4 \times 10^{-7}$

The energy is $100 \mathrm{eV}$ for $7 \times 10^{-7} \mathrm{~m}$,

e) The wavelength range if from $7 \times 10^{-7} \mathrm{~m}$ to $7 \times 10^{-14} \mathrm{~m}$ for infrared radiation

$100 \mathrm{eV}$ is The energy for $7 \times 10^{-7} \mathrm{~m}$.

$10^{-3} \mathrm{eV}$ is the energy for $7 \times 10^{-14} \mathrm{~m}$

f) The wavelength range is $1 \mathrm{~mm}$ to $0.3 \mathrm{~m}$ for microwaves

$10^{-3} \mathrm{eV}$ is the energy for $1 \mathrm{~mm}$.

$10^{-6} \mathrm{eV}$ is the energy for $0.3 \mathrm{~m}$.

g) For radio waves, the wavelength ranges from $1 \mathrm{~m}$ to few $\mathrm{km}$.

For $1 \mathrm{~m}$, the energy is $10^{-6} \mathrm{eV}$.

The photon energies for distinct regions of a source’s spectrum reflect the spacing of the source’s relevant energy levels.