Electrostatics/Electromagnetism. (BR 8.6b)

[ValiDemeanor]

Advertisement - Members don't see this ad

Hey guys, quick question please.

Example 8.6b on BR

Ok so I understand the relationship between dielectric constant (K) and Electrostatic force (F). The larger the dialectic constant, the smaller the force.

This can be derived from F= (kq1q2)/(Kr^2)

I eliminated A and B, so I know the answer is between C and D, I actually chose C to be the answer. (Correct answer is D)

My train of thought was... "Ok, if I had to pick between Medium A and Medium B, I would say that medium A's Force (F) is smaller" (I really didn't know how to determine which force was smaller [this is the main reason I missed this problem], but since the solid line (Medium A) was consistently farther away from F, I figured Medium A's force was smaller than Medium B's force)

With that being said, I figured since Medium A's force is smaller, it has a larger dialectic constant (K). That's option C.

Well, the book says the answer is D. How? Am I missing something simple that shows that Medium B's Force is larger?

If anyone could help that would be greatly appreciated. Thanks

 

[milski]

For any point of either curves, the X-coordinate is the distance and the Y-coordinate is forces experienced at that distance. Draw a [imaginary] vertical line at any point on the graph - the Y-coordinate intersection with the solid line is the force experienced in media A and the intersection with the dashed line - in media B. Since the solid line is always on top of the dashed line, the forced in media A is always larger than the force in media B.

 

[ValiDemeanor]

For any point of either curves, the X-coordinate is the distance and the Y-coordinate is forces experienced at that distance. Draw a [imaginary] vertical line at any point on the graph - the Y-coordinate intersection with the solid line is the force experienced in media A and the intersection with the dashed line - in media B. Since the solid line is always on top of the dashed line, the forced in media A is always larger than the force in media B.

Awesome, makes perfect sense. Thank you very much!