Consider two very long cylindrical wires (see image) of radius R, with current moving in the same direction. The centers of the wires are a distance 4R apart. Both wires have a uniform current density Jo. In the image, the line connecting the centers of the wires is an imaginary line to help visualize distances. a. What is the magnetic field at point (a), midway between the wires? b. What is the magnetic field at point (b) which is a point R/3 from the center of the left wire along the line connecting the two wire centers? c. What is the magnetic field at point (c), the center of the left wire? Side view current flows right Cross - Section View current into page -42

Two long, straight wires cross each other at a right angle, and each carries the same current I . Which of the following statements is true regarding the total magnetic field due to the two wires at the various points in the figure? More than one statement may be correct. a.The field is strongest at points B and D. b.The field is strongest at points A and C. c.The field is out of the page at point B and into the page at point D. d.The field is out of the page at point C and out of the page at point D. e.The field has the same magnitude at all four points.

6. In the velocity selector, what should be the direction of a magnetic field so that the particle will travel upwards (in the +y direction) undeflected?

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.