Cho 2 dòng điện thẳng dài vô hạn song song với nhau đặt cách nhau 5cm, cường độ của 2 dòng điện đó bằng nhau và bằng I=10A. Xác định vectơ cảm ứng từ B gây ra bởi các dòng điện đó tại 1 điểm A nằm ở giữa 2 dòng điện trong các trường hợp sau a/ các dòng điện chạy cùng chiều
b/ các dòng điện chạy ngược chiều

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?

To understand the behavior of the electric field at the surface of a conductor, and its relationship to surface charge on the conductor. a conductor is placed in an external electrostatic field. the external field is uniform before the conductor is placed within it. the conductor is completely isolated from any source of current or charge. part a: which of the following describes the electric field inside this conductor? it is in the same direction as the original external field.it is in the opposite direction from that of the original external field.it has a direction determined entirely by the charge on its surface.it is always zero. part b: the charge density inside the conductor is: 0non-zero; but uniformnon-zero; non-uniforminfinite part c: assume that at some point just outside the surface of the conductor, the electric field has magnitude e and is directed toward the surface of the conductor. what is the charge density η on the surface of the conductor at that point? express your answer in terms of e and ϵ0

Explain how a step-down transformer makes electricity safe for use in homes