1. The current in the wire shown below is 10.0 A. Find the magnetic field B at the point P from each wire segment, and sum them to find the total magnetic field B. 5cm . . 2.5cm I 2. A long straight wire carries a current of 20 A as shown. A rectangular coil with two sides parallel to the straight wire carries a current of 5 A. Find the force on each segment of the rectangular coil and the net force on the coil. I =20A =5cma I=5A 20cm 3. Helmholtz coils consist of two identical coils separated by a distance equal to their radius and carry the same current such that their axial fields add together (don't cancel in other words). A feature of such Helmholtz coils is that the resultant magnetic field between the coils is very uniform. Let R = 50 cm, I=100A and N=200 turns for each coil. Place one coil in the yz plane with its centre at the origin and the other in a parallel plane at x = 50 cm. (a) Calculate and graph the resultant field Bx for -50 cm < x < 100 cm. 4. A metal strip 1.0 cm wide and 0.1 mm thick carries a current of 5 A in a uniform magnetic field of 4.0 T which is applied normal to its width. The Hall emf measured across the width is observed to be 4.75 V. (a) Calculate the drift velocity of the electrons in the strip. (b) Find the density of charge carriers in the metal strip.