Help with E&M Questions: Answers, Explanations & Reviews

[compscier]

Help with E&M?
1) http://tinyimage.net/images/25790944428468568236.png
I don't even... The answer is B.. What should I review??

2)http://tinyimage.net/images/81684598844478119651.png
Why can't I use the formula V^2/R for this one?? answer C btw ( I did get it right, but just because I didn't see the answer choice I needed had I used V^2/R...)

3)http://tinyimage.net/images/14929814429358178541.png
How do I approach questions like 52? The answer is E... (I get 51 though)

4)http://tinyimage.net/images/89661487184785817963.png
Umm... I don't remember learning this.. What is this an application of?

5)http://tinyimage.net/images/05849919813601766271.png
57:B -> Why is R2 ignored? I put A originally...
58:A -> I thought there is no current after a significant amount of time b/c capacitor takes up all the charge? no?

 

[SammyS]

That's a lot of stuff for one thread !

 

[compscier]

they are sort of simple questions... I guess I'll make separate threads for each then...

 

[SammyS]

Help with E&M?
1) http://tinyimage.net/images/25790944428468568236.png
I don't even... The answer is B.. What should I review??

Maxwell's correction to Ampere's Law.

2)http://tinyimage.net/images/81684598844478119651.png
Why can't I use the formula V^2/R for this one?? answer C btw ( I did get it right, but just because I didn't see the answer choice I needed had I used V^2/R...)

Read the question. Its wording basically tells you to use I²R, where R is written in terms of resistivity, length & cross-section.

3)http://tinyimage.net/images/14929814429358178541.png
How do I approach questions like 52? The answer is E... (I get 51 though)

Do you know how to calculate electric potential?

4)http://tinyimage.net/images/89661487184785817963.png
Umm... I don't remember learning this.. What is this an application of?

Review your notes. How is electric potential related to potential energy?

5)http://tinyimage.net/images/05849919813601766271.png
57:B -> Why is R2 ignored? I put A originally...

Initially the potential across the capacitor is zero -- like a short circuit.

58:A -> I thought there is no current after a significant amount of time b/c capacitor takes up all the charge? no?

Eventually, the capacitor will not charge anymore, so there is no current through it, but there is still current through R₂.