Electricity is distributed from electrical substations to neighborhoods at 1.6×104 v . this is a 60 hz oscillating (ac) voltage. neighborhood transformers, seen on utility poles, step this voltage down to the 120 v that is delivered to your house. part a how many turns does the primary coil on the transformer have if the secondary coil has 140 turns? express your answer using two significant figures. n prim n p r i m = nothing turns submitrequest answer part b no energy is lost in an ideal transformer, so the output power p out from the secondary coil equals the input power p in to the primary coil. suppose a neighborhood transformer delivers 230 a at 120 v . what is the current in the 1.6×104 v line from the substation? express your answer using two significant figures. i i i i = nothing a submitrequest answer provide feedback next

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.)