Recent content by prodo123

Thanks! I took a look at Reif, and he specifically explains the differences between his approach and mine. It's making much more sense. The prof. and Reif both do not take into account reflections at the boundaries, which restricts allowed values of ##x## to multiples of the whole wavelength...

Not many people understood his proof in class, and the textbook's proof wasn't very clear so we went by with other derivations online. Then he filled half the midterm with his method, so I'm trying to understand how he did things. Looking back it seems very similar to the proofs we found online...

Found solution slides here: http://clas.sa.ucsb.edu/docs/default-source/Vince-Physics/30-1-physics-4-inductanceE0239A696CF5.pdf?sfvrsn=2 Used the wrong current formula. Correct formula is: ##i(t)=I_0(1- e^{\frac{-tR}{L}})##

Homework Statement A 35.0 V battery with negligible internal resistance, a 50 Ω resistor and a 1.25 mH inductor forms a RL circuit. How long will it take for the energy stored in the inductor to reach one-half of its maximum value? Homework Equations ##i(t)=I_0 e^{\frac{-tR}{L}}##...

Yes, the external field ##\vec{B}## in the equations is the B-field due to the current in the coils only.

The textbook doesn't discuss at all H-fields, so if I read what's online correctly, Para- and diamagnetism have B- and H-fields proportional such that ##\vec{B} = \mu \vec{H}##. The external field ##\vec{B}## is therefore equal to ##\mu_0 \vec{H}##. ##M=\chi H = \chi\frac{B}{\mu_0}## ##M =...

Sorry for the confusion, all the fields are B-fields, let me revise...maybe that's the issue? ##\int \vec{B}\cdot d\vec{l}=\mu_0 N I## ##BL=\mu_0 \lambda L I## ##B=\mu_0 L I## ##B=1.13\text {mT}##

Homework Statement A long solenoid of 60 turns/cm carries a current of 0.15 A. It wraps a steel core with relative permeability ##\mu_r=5200##. Find the magnitude of the magnetization of the core. Homework Equations ##N=\lambda L## ##\chi = \mu_r-1## ##\mu = \mu_r\mu_0##...

##A_{\text{sphere}}=R^2\iint sin(\theta)d\theta d\phi## where ##\pi \ge \theta \ge 0## and ##2\pi\ge\phi\ge 0## for an infinitely thin spherical shell Leaving ##\phi## as a variable gives the following: ##A=2R^2\int d\phi## ##dA = 2R^2 d\phi## ##q=\sigma A## ##dq = \sigma dA = 2\sigma R^2...

Homework Statement Sorry, the post isn't about a single homework problem but rather something that I keep getting confused on. It's about calculating the electric potential of a spherical shell of uniform charge in two different ways. Homework Equations ##\Delta V=\int_a^b -\vec E\cdot d\vec...

Integrating ##\vec E \cdot d\vec r## where ##\vec E = \vec 0## to find the potential at a single point results in ##V = 0+C##. Then the nonzero potential found at the center is ##C## and is constant across the space inside the shells... Makes much more sense, thanks!

Homework Statement Q1: There are two concentric spherical shells with radii ##R_1## and ##R_2## and charges ##q_1## and ##q_2## uniformly distributed across their surfaces. What is the electric potential at the center of the shells? Q2: There is an infinitely long hollow cylinder of linear...

Here's a comparison of the roots for ##y(x)=y_A+y_B, f=784\text{ Hz}##, assuming an arbitrary amplitude of 1 for both waves, found at different values of ##t##. The given set of roots include ##x(4)=0.026## and ##x(5)=0.534## (blue); the root in question is ##x(-5)=0.37788## (red). at ##t=0##...

Sorry, I got confused, it's for 784 Hz. Showing that ##x(-5)## is indeed equal to ##-x(6)##: ##x(-5)=\frac{4*784}{344(2(-5)-1)}-\frac{344(2(-5)-1)}{4*784}\\ x(-5)=\frac{3136}{-3784}-\frac{-3784}{3136}\\ x(6)=\frac{4*784}{344(2(6)-1)}-\frac{344(2(6)-1)}{4*784}\\...

Yes, I know from experience but that's not what the question is asking for and including it will give the wrong answer to the problem. Sorry, meant to say symmetry across ##x=0##. After some discussion and playing around with the graph of ##y_A+y_B## I concluded on the following: Diagram...