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photoelectric emission

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winnie101:
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

Deadly_king:

--- Quote from: winnie101 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

--- End quote ---

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

Hence Power = x where = photon energy =  /lambda

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

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

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

winnie101:
thank u so much

Deadly_king:

--- Quote from: winnie101 on December 02, 2010, 02:49:12 pm ---thank u so much


--- End quote ---

Anytime :)

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