What do wind turbines, hydroelectric dams, and ethanol plants have in common? A. All produce electrical current without pollution. B. All use generators to produce electrical current. C. All convert gravitational potential energy to electrical current. D. All convert thermal energy to electrical current.

When a vertical beam of light passes through a transparent medium, the rate at which its intensity i decreases is proportional to i(t), where t represents the thickness of the medium (in feet). in clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity i0 of the incident beam. what is the intensity of the beam "10" feet below the surface? (give your answer in terms of i0. round any constants or coefficients to five decimal places.)