Calculation of Energy of a Photon
To calculate the energy of a photon, we can use the formula:
\[ E = \frac{pc}{\sqrt{p^2c^2 + (m_0c^2)^2}} \]
where:
- \( E \) is the energy of the photon,
- \( p \) is the momentum of the photon,
- \( c \) is the speed of light in vacuum,
- \( m_0 \) is the rest mass of the photon.

Given Data:
- Momentum of the photon, \( p = 2 \times 10^{-16} \) gm-cm/sec
Now, we know that the rest mass of a photon is zero, so the formula simplifies to:
\[ E = pc \]

Calculation:
- Substitute the given value of momentum:
\[ E = 2 \times 10^{-16} \times 3 \times 10^{10} \]
\[ E = 6 \times 10^{-6} \, \text{gm-cm}^2/\text{sec} \]
To convert the energy to more common units like Joules, we need to convert it to kg-m/s:
\[ 1 \, \text{gm-cm}^2/\text{sec} = 10^{-7} \, \text{J} \]
\[ E = 6 \times 10^{-6} \times 10^{-7} \, \text{J} = 6 \times 10^{-13} \, \text{J} \]
Therefore, the energy of the photon is \( 6 \times 10^{-13} \, \text{J} \).