Physics

Problem

A beam of red light with a wavelength of

650\,\text{nm}

contains

2.50\times10^{20}

photons. What is the total energy of this beam expressed in kJ? a)

0.765\ \text{kJ}

0.00765\ \text{kJ}

0.0765\ \text{kJ}

0.48\ \text{kJ}