Một chiếc xe hơi đang chạy đang chạy qua một khúc cua có dạng cung tròn. Nếu xe chạy với tốc độ không đổi 50km/h thì gia tốc của nó sẽ khác thế nào so với khi chạy tốc độ 80km/h . Xe có thể chạy với tốc độ cao nữa không?Vì sao

iron would move it is magnetic there is a mag field around the current in the wire

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia