The current density inside a cylindrical wire of radius R changes as j = ar, r being the radial distance to the center of the wire and a being a constant. (a) Calculate the curent in the wire at a distance r from the center of the wire. i (b) What is the magnitude of the magnetic field produced by the current at a distance r inside the wire? (c) Calculate the magnitude of the magnetic field at a distance r outside the wire. (d) Graph B(r) as a function of r fromr = 0 to r = 3R.

A strip of copper 220 um thick and 4.70 mm wide is placed in a uniform magnetic field of magnitude B = 0.96 T, that is perpendicular to the strip. A currenti- 25 Ais then sent through the strip such that a Hall potential difference Vappears across the width. Calculate V. (The number of charge carriers per unit volume for copper is 8.47 x 102 electrons/m) Number Units

-9 the positive x-direction. the negative x-direction. O the positive y-direction. O the negative y-direction. O out of page O into the page O y V I X A long straight wire lies along the x-axis and carries current in the negative x-direction. A negative point charge moves along the y-axis in the negative y-direction. The magnetic force that the wire exerts on the point charge is in

The two wires shown in the figure below are separated by d = 12.5 cm and carry currents of I = 4.80 A in opposite directions. P1 - 2d- -d (a) Find the magnitude and direction of the net magnetic field at a point midway between the wires. magnitude uT direction --Select-- (b) Find the magnitude and direction of the net magnetic field at point P,, 12.5 cm to the right of the wire on the right. magnitude μτ direction |---Select--- (c) Find the magnitude and direction of the net magnetic field at point P,, 2d = 25.0 cm to the left of the wire on the left. magnitude uT direction ---Select---