(Solved): Activity 3 The Magnetic Field due to a Coil of Wire In practice, it is often useful to know about t ...

Activity 3 The Magnetic Field due to a Coil of Wire In practice, it is often useful to know about the magnetic field due to a coil of wire. A current-carrying coil of wire, an electromagnet, can produce strong B fields that can be turned off and on. Electromagnets have many practical applications, e.g., driving an electric motor. In this activity, you'll work through the concepts, step-by-step. 1 From activity 2, you learned the shape of B surrounding a straight current-carrying wire. Keeping that picture in mind, imagine bending that wire into a curve: B Q12 For the figure above, is "B" more "concentrated" on the inside or on the outside of the curve? Now take that wire and bend it into a single loop, still imagining the surrounding B. The B field lines point out of the page inside the loop. The B field lines point into the page outside the loop: x One more step: Imagine that you rotate the loop, looking at it edge-on so that the B inside of the loop points to the right. Note that in the diagram directly to the right, the current flows up the back of the loop and down the front. Q13 Circle the correct the basic shape of B surrounding this single loop of wire. B B B B B B Q14 Now, sketch the basic shape of B surrounding the following coil of wire, made of several adjacent loops, with current flowing from B to A. gump B Q15 Set up to test the directions of B from your sketch of "Q14". Wire a solenoid (closely wound coils of wire) as shown below. Use your compass as a B tester. Sketch the direction of B at each of the following positions shown. Note, if you find that B points opposite to the directions that you predicted, your solenoid may be wound opposite, or your current may be flowing opposite to the sketch of "Q14". Determine the source of the discrepancy and fix it. O ? Q16 Compare the magnetic fields drawn in Q3 and Q15. How does the magnetic field created by current running in a solenoid compare to magnetic field created by a bar magnet? Explain. Q17 Suppose that two identical parallel wires each carry a current I as shown below. At each of the five points indicated, label the direction of Baet due to the two wires. Hint: Remember that Bwire Hodepends on "d", so that Buet does not cancel at the leftmost or rightmost point! = 2n d Q18 If the two wires above each carry a current of 2 A, and are 4 cm apart, determine the magnitude of Bnet midway between the two wires. Show your work: