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Grade 12Wave Motion

average wavelength of light emitted by a 100 watt bulb is 5,000 A^0 . the number of emitted photons per second :
(1) 5*10^17 (2) 2.5*10^22 (3) 3*10^23 (4) 2.5*10^19

Profile image of jayprakash pal
8 Years agoGrade 12
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1 Answer

Profile image of Venkat
ApprovedApproved Tutor Answer8 Years ago
Power of bulb is given as 100 watt. Calculate the energy first and then no.of photons.
Energy of one photon is
 
E=h\frac{c}{\lambda } = \frac{6.626*10^{-34}*3*10^{8}}{5000*10^{-10}}=3.975*10^{-18}
No.of photons emitted per second is
=\frac{100}{3.97856*10^{-18}} = 2.515*10^{19}