Wo small pith balls, each carrying a charge q, are attached to the ends of a light rod of length d, which is suspended from the ceiling by a thin torsion- free fiber. There is a uniform magnetic field B, poi If the magnetic field is turned off, which of the following describes what happened to the system? nting straight down, in the cylindrical region of radius R around the fiber. The system is initially at rest TrueIt does not rotate because to do so would violate conservation of angular momentum FaiseIt rotates with angular momentum qBd/4 True It does not move because magnetic forces do no work Fase It rotates with angular momentum qBR True It rotates with angular momentum qBRd/2

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.)