Day 10 Electric Flux

We had to draw a picture that represents electrical flux and what it meant.

Flux can be though of the lines of electricy passing through. If lines going in are = to lines going out flux is zero. If there is any disrepcancy positive or negative then the flux if positive or negative.

Dipole if q+ and q-. Finding if there is going to be a torque.

We did some math to find an expression for torque.

Continuation of work, we used cross product r x f.

Picture of Prof. Mason work of dipole torque. Much cleaner and easier to see.

Torque becomes - 2aqEsintheta

We then did some Active Physics lab and questions. One of the demo question was to find work as it spins.

Work is equal to rho*E(costheta inital - costheta final).

We then had to find Ey and find an expression for it.

Ey = KQD/ (d^2+ a^2)^(3/2). This expression was similar to the one of gravity from 4A.

 We then moved on to a demonstration of the Van de Graaff generator. We had to make some prediction of what would happen to aluminum out side. We said the ones inside would stick inside and the ones out side would repel against the cage.

Picture before its on the device.

Shows that the ones inside are stuck to the wall of it and the ones outside are repelled by it. Our prediction were right.

Calculus work from before and our prediction on white board.

We then moved on to working out some Active Physics problems. We had to draw flux lines when there was different q.

This one had q, 2q and 4q thus the there had to be more lines extending outwards.

We then had to draw the connection of different charges and their flux.

We had +q and -q. The flux lines went from positive to negative.

Prof. Mason then showed how cool he was by setting on spikes. They represent flux.

Where he is going to sit.

Him being a boss.

We then had to answer some question from the demos by Active Physics lab. The following white board have the answers.

Playing with the Active Physics demo; Answer to number 1.

Playing with Active physics demo; Answer to number 2.

Playing with Active Physics demo; Answer to number 3.

The same as above, Answers for 5,6,7 and 8.

Flux is equal to EA = E4pir^2
We then found the flux of a cube.

Only the E on the left side and right side matter. All the other sides had no E "lines" going through them thus they were zero. Flux then became EA - EA which turns out to be zero.

Summary:
A dipole experinces a toruqe. Torque is = -2aqEsintheta. Work is = rho*E(costheta inital - costheta final).
We found an expression for Ey =  Ey = KQD/ (d^2+ a^2)^(3/2) which looks similar to the gravity integral we used in 4A.
Did an experiment with the Van de Graaff generator. Our predictions work correct. Inside sticks, outside repels.
Did a whole bunch of Active Physics Demos. Learned that Flux is zero when there is no charge. Flux is related to the magnitude of charge. Flux depends on the summation of charges inside a ring. Flux = EA.
Flux only effects areas that are on its "way".