Electricity & Magnetism Resource Packet Contents by Topics

**Forces between charges, or from electric fields**

**Electric fields created by charges or dipoles**

- Electric field plots of three point charges using 'short arrows' to represent the field.
- Electric field of N charges along a line (Excel)
- Electric field and electric flux of a point charge (Excel)

**Electric potential**

- plot the potential from a point charge not at the origin by shifting coordinates
- calculate V from long charged rod; obtain E from V.
- build a 'wall' to protect against invading protons, using a fixed total charge
- calculate V f rom long charged rod and do a contour plot
- given E field, find potential difference
- use line integral to find potential difference
- contour plot of electric potential from two point charges
- integrate to obtain the potential at a point due to a charged rod
- shift coordinates to obtain 3D potential plot when charges are moved
- make a 3D contour plot for 3 charges; locate equilibrium points
- make a 3D contour plot for 3 charges; find where Ex and Ey are zero
- try to trap a charge inside a box with charges at the 8 corners

**Capacitance, Dielectrics**

- Plot the capacitance of concentric spheres as a function of outer radius.
- Concentric spheres partly filled with dielectric
- integrate 'through'' a dipole 'layer' to find the net potential difference from a dielectric

**Resistors, DC Circuits**

- analyze currents in resistors
- current flow in a slab resistor
- given some currents in a DC circuit, find the remaining ones
- given some potential differences in a DC circuit, find the others

**RC circuits**

- Use RC circuit to 'demodulate' an incoming signal and obtain the 'envelope'
- RC circuit as a filter for various frequencies
- Examine noise with a R-C circuit

**Magnetic fields created by currents**

- integrate to find the magnetic field of a circular current loop
- 3-D plot of magnetic field in a helmholtz coil arrangement
- if you are close enough to one side of a rectangular loop, it acts like an infinite wire
- use derivatives to find the maximum slope (inflection point) on the axis of a circular loop
- integrate using Biot-Savart law to find B due to half of a current loop
- 3D plot of magnetic field in and around helmholtz coils
- In a rectangular loop, how close to one side must you be for the wire to look 'infinite'
- Create a 'loose' solenoid' of 2, 3, and 5 coaxial current loops

**Motion of charges in electric or magnetic fields**

- path of a particle in E and B fields (path in any E, B, v combination)
- path of a drop of ink under E field in an ink-jet printer
- electrostatic precipitator

**Faraday's law**

- which pickup coil will be effective?
- Can you extract power with a pickup coil near a power line?
- Lawnmower spark from magnets moving past a coil (maple)
- Lawnmower spark from magnets moving past a coil (Excel)

**Inductance**