1. A phonograph record of radius R, carrying a uniform surface charges, is rotating at constant angular velocity w. Find its magnetic dipole moment. 2. If B is uniform, show that

A=(rX B), where r is the vector from the origin to the point in question. That is, check that B=V x A and V.A = 0. 3. In a certain conducting region, H = yz(x² + y²), - y²xza, + 4x²y²a₂ A/m (a) Determine J at (5, 2, -3) (b) Find the current passing through x = -1,0