Hai dòng điện có cường độ I1=2A, I2=4A chạy trong hai dây dẫn thẳng dài vô hạn, đồng phẳng, vuông góc với nhau đặt trong không khí. Trong mặt phẳng chứa hai dòng điện, quỹ tích những điểm tại đó vec tơ cảm ứng từ tổng hợp bằng 0 là đường thẳng( trừ điểm gốc tọa độ o):

Because air contracts as it cools, the air pressure inside a freezer is typically lower than on the outside. why do ice cubes inside a freezer tend to shrink over time? a. the ice dissolves oxygen from the air, forming a denser crystalline matrix.b. the ice reacts chemically with carbon dioxide in the air, forming gaseous carbon compounds.c. the ice melts, and then the liquid freezes as ice crystals on the bottom of the freezer.d. the ice sublimes, and then the water vapor deposits as ice crystals on the sides of the freezer.

How is the ideal mechanical advantage of a wheel and axle calculated?

20) what is a magnetic field? 21) in which direction do magnetic field lines always point? 22) sketch a diagram showing how a plotting compass points around a 23) name two magnetic poles that will: a) attract each other b) repel each other. 24) explain why you can use a compass to navigate. 25) what's an electromagnet? 26) list two ways to increase the strength of an electromagnet. 27) the wire in a simple motor feels a force when a current flows through it. why is this? i need answers to check mine