Problem 4 A circular loop of wire with radiusR is in a uniform magnetic field with magnitude B that points in the positive z-direction. The loop is initially in the xy-plane and carries a constant, unknown current. Flipping the loop over requires you to do positive work (W). Determine the current in the loop.

C. it comes from the core of the earth.

In atoms, the electron carries a negative elementary or unit charge; the proton carries a positive charge. the two types of charge are equal and opposite. in an atom of matter, an electrical charge occurs whenever the number of protons in the nucleus differs from the number of electrons surrounding that nucleus.