Why does a siren have a lower pitch as it moves away from you? A The period of the sound wave is decreased B The amplitude of the sound wave is increased C The crests of the sound wave are farther apart D The troughs of the sound wave are spaced closer together.

Ametal ring 4.20 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. these magnets produce an initial uniform field of 1.12 t between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.240 t/s . (a) what is the magnitude of the electric field induced in the ring? (b) in which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?