Which statement is true about the turbine in a hydroelectric dam? a. it is turned by wind and provides a direct current. b. it is turned by water to produce a direct current. c. it is turned by water to turn a wire inside a magnet. d. it is turned by wind and provides an alternating current.

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.