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

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The discussion focuses on clarifying concepts related to electromagnetism (E&M) questions. Participants seek help with specific problems, sharing their answers and confusion about formulas like V^2/R and I2R. Key points include the importance of understanding electric potential and its relation to potential energy, as well as the behavior of capacitors in circuits. There are also inquiries about why certain resistances are ignored in calculations. Overall, the thread emphasizes the need for a solid grasp of fundamental E&M principles to tackle these questions effectively.
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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?
 
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That's a lot of stuff for one thread !
 
they are sort of simple questions... I guess I'll make separate threads for each then...
 
compscier said:
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.
 
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Thread 'Errors and significant figures'

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Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
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