Question

For what wavelength of light does a 100 mW laser deliver $2.50\times {10}^{17}$photons per second?

Short answer

Wavelength of light is 497 nm.

Step-by-step solution

Step 1. Given information is :100 mW laser is delivering 2.50×1017photons per second.

We need to find out the wavelength of light.

Step 2. Using the expression of energy of photon

$$\begin{gathered} E_{ph}=\frac{P}{R} \\ {E}_{ph}=\frac{hc}{\lambda } \\ \frac{hc}{\lambda }=\frac{P}{R} \\ \lambda =\frac{hcR}{P} \\ \lambda =\frac{\left(6.63\times {10}^{-34}\right)\left(3\times {10}^{8}m/s\right)\left(2.50\times {10}^{17}\right)}{\left(100\times {10}^{-3}W\right)} \\ \lambda =497nm \end{gathered}$$