Which of the following statements about electric charge is true? A. Objects must be touching on another to exert electrical force. B. Electrical forces act at a distance. C. Air cannot conduct electricity; it is conducted only by solid materials. D. Opposite electric charges always repel one another.

Aray diagram for a refracted light day is shown. what does the dashed line represent

Copper has free electrons per cubic meter. a 71.0-cm length of 12-gauge copper wire that is 2.05 mm in diameter carries 4.85 a of current. (a) how much time does it take for an electron to travel the length of the wire? (b) repeat part (a) for 6-gauge copper wire (diameter 4.12 mm) of the same length that carries the same current. (c) generally speaking, how does changing the diameter of a wire that carries a given amount of current affect the drift velocity of the electrons in the wire?

Apulley with a mechanical advantage of 5 will require you to pull times the amount of rope. a. 1/5 b. 5 c. 10 d. 15