Question

A square coil, 4.0 cm meters on a side, is made from a 3.0 meter length of wire. The resistance of the wire is 0.25 ohms.

a) Determine the approximate number of loops in the wire (round to nearest whole number) and the area of each loop (in meters!) to 3 significant figures. Use these numbers in the parts below.

A horizontal wire sits on the table 8.5 cm away from the center of the coil, carrying a steady 0.40 A of current (this is called “direct current”). For consistency, let’s say the wire is along the x-axis, with the current traveling to the right (+x). The loop is located in front of the wire from your perspective (+z). Both the straight wire and coil are laying down on the table (in other words, as you look down on the table you see through the coil. The y-axis is going through the table.

b) Draw this situation.

c) Determine the magnetic flux through the coil. Hint: this takes a few steps. A good idea is to start by figuring out the magnetic field generated by the long wire at the location of the coil.

d) Determine the magnitude and direction of the current induced in the coil.

Now, the wire’s current changes direction, sloshing back and forth, such that it makes 60.0 complete cycles every second (this is called “alternating current”).

e) When the current in the wire goes from 0.40 A in the +x direction to 0.40 A in the –x direction once, determine the magnitude and direction of the average current induced in the coil, as seen from above.

Answer 1