A 200W sodium street lamp emits yellow light of wavelength 0.6 mm. Assuming it to be 25% efficient converting electrical energy to light, the number of photons of yellow light it emits per second is___________
A. 62 × 10²⁰
B. 3 × 10¹⁹
C. 1.5 × 10²⁰
D. 6 × 10¹⁸
Answer:C
A 200W sodium street lamp emits yellow light of wavelength 0.6 mm. Assuming it to be 25% efficient converting electrical energy to light, the number of photons of yellow light it emits per second is___________
A. 62 × 10²⁰ B. 3 × 10¹⁹ C. 1.5 × 10²⁰ D. 6 × 10¹⁸