A sodium vapour lamp rated at emits light of wavelength
PHYSICS · Subjective · CBSE · Physics · Dual Nature of Radiation and Matter · Dual Nature of Radiation and Matter
Problem
A sodium vapour lamp rated at 100W emits light of wavelength 589nm. Only 30% of the electrical power is converted into light at this wavelength; the rest is lost as heat. The entire light from the lamp falls normally on the cathode of a photocell whose quantum efficiency is 5% (i.e. only 5% of the incident photons release photoelectrons).
(i) Calculate the energy of one photon emitted by the lamp.
(ii) Compute the number of photons emitted per second by the lamp.
(iii) Determine the photocurrent produced in the external circuit of the photocell under these conditions.