10. In Experiment II, starting when the bar is suspended, what will be observed when the switch between points a and f is opened?
A. The current through the bar remains the same, so the bar remains stationary.
B. The current through the bar goes to zero, and the bar descends to the bottom of the rails.
C. The current through the bar decreases slightly and the bar descends the rails.
D. The current through the bar increases slightly and the bar ascends the rails.
I got the correct answer but I was wondering why the second part of the answer was true.
The passage said:
"In order to support the idea of Lenz's law, when the switch between points a and f was open, the bar slid down the rails unimpeded in Experiment I. In Experiment II, the bar did not move unless the voltage source was connected."
So from that I thought it meant that unless the circuit was connected, the bar wouldn't move. I picked B because when the current gets disconnected, the current goes to 0.
The answer said:
Choice B is the best answer. In Experiment II, before the switch between a and f is opened, there is current flowing betweenpointsaandfthatisintheoppositedirectionofthecurrentbetweenpointsXandY. Oncetheswitchisopened,the current stops and there is no longer a force suspending the bar. Without any force holding the bar up, it will slide down the rails due to gravity, eventually reaching the bottom. The best answer is choice B.
A. The current through the bar remains the same, so the bar remains stationary.
B. The current through the bar goes to zero, and the bar descends to the bottom of the rails.
C. The current through the bar decreases slightly and the bar descends the rails.
D. The current through the bar increases slightly and the bar ascends the rails.
I got the correct answer but I was wondering why the second part of the answer was true.
The passage said:
"In order to support the idea of Lenz's law, when the switch between points a and f was open, the bar slid down the rails unimpeded in Experiment I. In Experiment II, the bar did not move unless the voltage source was connected."
So from that I thought it meant that unless the circuit was connected, the bar wouldn't move. I picked B because when the current gets disconnected, the current goes to 0.
The answer said:
Choice B is the best answer. In Experiment II, before the switch between a and f is opened, there is current flowing betweenpointsaandfthatisintheoppositedirectionofthecurrentbetweenpointsXandY. Oncetheswitchisopened,the current stops and there is no longer a force suspending the bar. Without any force holding the bar up, it will slide down the rails due to gravity, eventually reaching the bottom. The best answer is choice B.
