I'm in electrophysics this summer and enjoying it, but getting

>>8981242
It's all music anon. Every last bit of it.
Music.

>>8981242
What don't you get?

>>8981257
I'm getting most of it with practice.

The main thing making me stumble is stuff like
>You have a half-circle of charge distribution of radius r
>Its charge is positive in the second quadrant and negative in the first quadrant
>What is the net electric field on a point charge at (0,0)? At (2,0)? at (-3, 3)?
>What net forces result on a positive point charge? A negative point charge?

I can sketch the problem just fine. And I know how the particles react, but converting the sketches to calculus just fucks me.

The charged line, the angle, and the X and Y values all change as you move around the circle. But somehow the infinitesimal changes in theta, x, and y should all balance our, or something? And the changes in charge can be converted from, say, dQ into lamba dL? Where Q is the charge and L is the length of the semi-circle?

I get symmetry. That stuff's cool. I like ignoring half the problem because of canceled forces. And I can solve the integrals after they're constructed.

It's just the construction in the first place that gets me. It's not just in Physics, either. In all of my STEM classes, constructing integrals for anything more complex than "work required to drain a cylindrical tank" is hit-or-miss for me, indicating I conceptually don't get it.

But again, I'm not here for help on a specific problem. Rather, I'd like to think more like someone who KNOWS electrophysics.

>>8981274
The strange bit being, when I ask my professors/TAs/tutors/classmates/etc about this they just tell me to plug the numbers in the formula we derived in class and that'll handle it.

But I cannot ever remember the formula we derived in class because I don't know what it works. I need to know how to derive it myself but for some reason the logic doesn't align.

Also: I lied. Apparently I can't work the calculus. r is variable, but I dunno what to do with it. Maybe it's contingent on x/y and cancels? idk.

[math] \vec{E}=\frac{\vec{F}_{e}}{q} \rightarrow \vec{E}=\frac{Q}{4\pi \varepsilon_{0}r^{2}} [/math]

[math] dQ=\lambda dL [/math]

[math] d\vec{E}=\frac{\lambda dL}{4\pi \varepsilon_{0}r^{2}}\rightarrow \int_{0}^{L}d\vec{E}=\frac{\lambda}{4\pi \varepsilon_{0}}\int_{0}^{L}\frac{dL}{r^{2}} [/math]