A beam of red light with a wavelength of contains photons

PHYSICS · Single correct · CBSE · Physics · Dual Nature of Radiation and Matter · Dual Nature of Radiation and Matter

Problem

A beam of red light with a wavelength of 650 nm650\,\text{nm} contains 2.50×10202.50\times10^{20} photons. What is the total energy of this beam expressed in kJ? (a) 0.765 kJ0.765\ \text{kJ} (b) 0.00765 kJ0.00765\ \text{kJ} (c) 0.0765 kJ0.0765\ \text{kJ} (d) 0.48 kJ0.48\ \text{kJ}

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