Question

Ha 120-W lightbulb emits 2.5% of the input energy as visible light (average wavelength 560 nm) uniformly in all directions Part A How many photons per second of visible light will strike the pupil (4.0 mm diameter) of the eye of an observer 1.0 m away? Express your answer using two significant figures. ΔΝ, At 8.3K1012 photons/s Previous Answers Correct N Part B How many photons per second of visible light will strike the pupil (4.0 mm diameters of the eye of an observer 1.0 km away? Express your answer using two significant figures. VALO AM A Photos/s Submit Reguest Answer

please answer part B - thanks!

Answer 1

Solution Here P= 2.5 100 x 120 - 3 581 B so 3181 4 mx (1•0x103)? 2.39 X 10 7 J/sm2 Now the power entering to the eye Peye 나 X A rege ² 2.39 x 10-7 X TX (2x103) 2 3.00810 ils Therefore N = Pege 6-12 2 3.0001012 6.626 X10-34 x 3X108 550 x 10-9 8.30*100 Photon I see