A incandescent bulb converts electrical energy into visible light with an overall…

PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation

Problem

60\,\text{W}

incandescent bulb converts electrical energy into visible light with an overall luminous efficiency of

16\%

. Spectral measurements reveal that only

4.0\%

of the emitted visible power is concentrated in a narrow band centered at a wavelength of

550\,\text{nm}

(green). The bulb is switched on and allowed to operate at the rated power for exactly

10.0\,\text{min}

. (a) Determine the optical power actually emitted in the

550\,\text{nm}

band. (b) Calculate the rate at which photons of wavelength

550\,\text{nm}

leave the bulb. (c) Compute the total number of such photons emitted during the

10.0\,\text{min}

operating interval. (d) A colored glass filter placed over the bulb transmits only

25\%

of the energy in this wavelength band. How many

550\,\text{nm}

photons exit the filter in the same time interval?