Two 1.50-V batteries—with their positive terminals in the same direction—are inserted in series into a flashlight. One battery has an internal resistance of 0.255 V, and the other has an internal resistance of 0.153 V. When the switch is closed, the bulb carries a current of 600 mA. (a) What is the bulb’s resistance? (b) What fraction of the chemical energy transformed appears as internal energy in the batteries?

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 1.90