Question

The two loops of wire in FIGURE are stacked one above the other. Does the upper loop have a clockwise current, a counterclockwise current, or no current at the following times? Explain. a. Before the switch is closed.

b. Immediately after the switch is closed.

c. Long after the switch is closed.

d. Immediately after the switch is reopened.

Short answer

(a) There is no magnetic flux change before the switch is closed.

(b) immediately after the switch is closed, current flows clockwise.

(c) long after the switch is closed, the current in the lower loop remains constant.

(d) Immediately after the switch is reopened, current flows in the opposite direction.

Step-by-step solution

Introduction

A switch loop is another term for a wiring circuit constructed to link a light fixture to a wall switch in layman's terms. Instead of pulling a cord every time you want to turn on or off a light, you simply flip a switch or press a button.

Explanation

(a) There is no current. Because there is no change in magnetic flux, no magnetic field is induced.

(b) clockwise. An increase in counterclockwise current in the lower loop causes an increase in the upper loop's upward pointing magnetic field. As a result of the clockwise current in the loop, a downward magnetic field is induced.

(c) There is no current. The current in the bottom loop is always constant. As a result, the flux via the top loop remains unchanged.

(d) counterclockwise. The lower loop's decreasing current leads the flux through the higher loop to drop, resulting in an upward magnetic field.