You are working in an optical research laboratory. your supervisor needs you to set up a double-slit apparatus for a presentation that will provide a vertically varying pattern of red light of wavelength 669 nm on a screen. the screen of width 4.75 m at the front of the presentation room must have red fringes on either end and 23 additional red fringes between those on the end. the separation between the slits in the double slit you will use at the back of the room is 60.0 µm. you need to determine how far away from the slits (in m) the screen must be placed. (assume the central maximum is at the center of the screen.)

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000

i think the answer is a and b

i wish you luck

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hope this !