Dual Nature of Matter and Radiation

Step 1: Understanding PowerPower is how much energy is used or given out each second. So: Power $= \frac{\text{ Energy }}{\text{ Time }}$Step 2: Energy of One PhotonThe energy in one photon of light is found using: $E = h f$ where $h$ is Planck's constant and $f$ is the frequency.Step 3: Total Energy from Many PhotonsIf $N$ photons come out in time $t$, the total energy is $N \times h f$.Step 4: Linking Power and Number of PhotonsSo, Power $= \frac{\text{ Total Energy }}{\text{ Time }} = \frac{N \times h f}{t}$Step 5: Average Number of Photons per SecondThe number of photons per second is $n = \frac{N}{t} = \frac{P}{h f}$ Plug in the numbers: $n = \frac{33 \times 10^{-3}}{6.6 \times 10^{-34} \times 5 \times 10^{14}}$Step 6: Final CalculationThis works out to: $n = 10 \times 10^{16}$ So, the laser gives off $10 \times 10^{16}$ photons every second.