Author Topic: photoelectric emission  (Read 692 times)

Offline winnie101

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photoelectric emission
« on: November 30, 2010, 12:48:30 pm »
could someone plz help me with the following
A particular filament rating of 60W emits 5% of this power as visible light. The average wavelength of visible light is 550nm.
Calculate the number of photons of visible light emitted per second from the lamp.
Thanks

Offline Deadly_king

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Re: photoelectric emission
« Reply #1 on: December 02, 2010, 10:52:13 am »
could someone plz help me with the following
A particular filament rating of 60W emits 5% of this power as visible light. The average wavelength of visible light is 550nm.
Calculate the number of photons of visible light emitted per second from the lamp.
Thanks

The 5% power is defined as the energy required for x number of photons to be emitted per second.

Hence Power = x x E where E = photon energy =  hc/lambda

Power = x x hc/lambda -----> 5/100 x 60 = x x (6.63 x 10-34) x (3 x 108) / (550 x 10-9)

Thus x is found to be 8.3 x 1018 which is the required answer.

Sorry for late reply...........but I was kinda busy. :-[

Offline winnie101

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Re: photoelectric emission
« Reply #2 on: December 02, 2010, 02:49:12 pm »
thank u so much

Offline Deadly_king

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Re: photoelectric emission
« Reply #3 on: December 02, 2010, 04:54:59 pm »