Mặt phẳng (P) đặt trong không khí, tích điện đều với mật độ điện mặt  = – 3,54.10 – 9 C/m2. Chọn gốc điện thế tại mặt phẳng (P); tính điện thế tại điểm M cách (P) một đoạn x = 40 cm.

Suppose a wire with a current is pushed upward by a magnetic field. how would the wire move if the direction of the current reversed? explain your answer.

When a pair of 10-n forces act on a box of candy, the net force on the box is a 20 n. b about 14 n. c zero. d any of the above depending on the directions of forces.

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space? the cloud is extremely hot. the cloud is visible primarily because it reflects light from nearby stars. the cloud is cool and lies between you and a hot star. the cloud is cool and very dense, so that you cannot see any objects that lie behind it.