It requires skill and eye coordination!!
Answer:
750 nm
Explanation:
= separation of the slits = 1.8 mm = 0.0018 m
λ = wavelength of monochromatic light
= screen distance = 4.8 m
= position of first bright fringe =
= order = 1
Position of first bright fringe is given as


λ = 7.5 x 10⁻⁷ m
λ = 750 nm
A). 1,000 watts = 1 kilowatt
5,000 watts = 5 kilowatts
b). (5 kilowatts) x (2 hours) = 10 kilowatt-hours (kWh)
c). (10 kWh) x (15 cents/kWh) = $1.50