Ivan Seeking

Staff Emeritus

Science Advisor

Gold Member

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## Main Question or Discussion Point

Here is a favorite of mine from college that I thought you might enjoy: Consider a closed square loop of wire with two resistors, R1 and R2, each located in-line and symmetric about the center of the loop. Two voltmeters each measure the voltage change, V1 and V2, across R1 and R2 respectively. The loop is positioned such that a constantly increasing magnetic field vector [dB/dt > 0] passes through the center of the loop causing current i to flow.

````````i -->

|----------------|

|``````````````|

|``````````````|

R1```(dB/dT)```R2

|```````X``````|

|``````````````|

|-----------------

We demand that: The conductor, resistors, and voltmeters are perfect, and that R1 is not equal to R2.

Here's the problem, if R1 not = to R2, then according to Ohm's law, since i is constant over the loop, V1 not = V2. But the voltmeters are connected in parallel, so it seems they must read the same. So do they read differently or the same and why? Sorry, the diagram didn't quite work.

I know this won't be hard for everyone.

````````i -->

|----------------|

|``````````````|

|``````````````|

R1```(dB/dT)```R2

|```````X``````|

|``````````````|

|-----------------

We demand that: The conductor, resistors, and voltmeters are perfect, and that R1 is not equal to R2.

Here's the problem, if R1 not = to R2, then according to Ohm's law, since i is constant over the loop, V1 not = V2. But the voltmeters are connected in parallel, so it seems they must read the same. So do they read differently or the same and why? Sorry, the diagram didn't quite work.

I know this won't be hard for everyone.

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