Ascreen is placed 50cm from a single slit illuminated with 690nm light. if the distance between the first and third dark fringes in the diffraction pattern is 3mm.
a) find the width of the slit
used w=(2\lambdal)/d to get 500 mm
b) find the width of the central bright fringe using w=(2\lambdal)/d .

What do butterflies have on their feet which allows them to sense different strengths and types of nectar? a.mechanoreceptors b.acoustic receptors c.substratum receptors d.chemoreceptors

Students design a model roller-coaster track. they place a rubber ball at the highest point on the track and let it go. the ball rolls along the track pulled only by the force of gravity. eventually, it comes to a stop. which change to the design will result in the ball moving the greatest distance?

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina.with the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 2.05cm in front of the eye.)