Consider the diagram below showing 2 two current loops (a square and circle centered about the same point. If the currents in each loop are in opposite directions and the current in the square loop is 3.13 A, what must the current in the circular loop be if the net magnetic field at the center is zero? Let the radius of the circle be 0.146 m.

A long, cylindrical conductor of radius R carries a current I as shown in the figure below. The current density J, however, is not uniform over the cross-section of the conductor but is a function of the radius according to J = 2br, where b is a constant? Find an expression for the magnetic field magnitude B at the following distances, measured from the axis. (Use the following variables as necessary: ?0, r1, r2, b, R.) (a) r1 < R (b) r2 > R

As shown in the figure below, a circular ring with a radius of a is folded along a line across the diameter so that the two semicircles are perpendicular. In the magnetic field, this ring was rotated at a constant angular velocity over time, as shown in the figure. The axis of rotation is an extension of the fold-off line and is perpendicular to the magnetic field. The resistance of the ring is R. (1) Give a qualitative explanation of what will happen. (2)Find the current flowing through the ring. (3)What torque should be applied to the ring to allow it to rotate at a constant angular speed? (4)What do you have to do to turn it N round? (5) What energy changes from ring to heat? (6) How much energy changes from ring to heat? * I'll be so thankful and satisfied to get answer just least 3 of 6 questions..

Consider a long, horizontal Large Wire with current of 10 A running through it. We want to levitate a horizontal, thin, 0.50 m length of wire above it. If the thin wire has a mass of 10 grams, and a current of 300 mA, how far above the Large Wire will it hover (net force of zero) due to magnetic and gravitational forces? A. If the thin wire hovers above the Large Wire due to their magnetic fields, are their currents going the same direction, or opposite directions. Explain. B. Draw a diagram and label the directions of currents, and all other relevant quantities and vectors. C. Find the distance above the Large Wire the small thin wire will hover (net force of zero). D. Would your answers to parts A and C change if we wanted to find a distance below (rather than above) the Large Wire that the smaller thin wire could hover, due to their magnetic fields. Explain. Don't calculate any values but draw a new diagram and explain how this situation compares to the problem above.

A particle of mass “M” and charge “+Q” Travels at a velocity “V” in a plane perpendicular to a Magnetic Field of magnitude “B” as shown in the Picture. The particle will experience motion on a circular path. (not the question just context, also the pic is for probelm 1.) Assume similar conditions as problem 1 but now the proton, moves along the magnetic field undeflected. This new behavior can only be explained if there exist an external electric field in addition to the magnetic field. What is the magnitude and direction of such field? (you can disregard gravity) (prob 2 is the question:) sorry if its confusing)