PHYS 1120 / 2020 Midterm 2 Study Guide

Voltage


Voltage from a point particle:


Voltage from an electric field:


* The only distance Δd that matters is the distance that is parallel to the electric field *


How voltage is related to work/energy:


If you need to find a particle’s speed from its voltage or energy, use the work-energy theorem from Physics 1:


Capacities


For a parallel-plate capacitor, THE ONLY THING THAT CHANGES CAPACITANCE IS A CHANGE IN THE AREA OF THE PLATES OR THE DISTANCE BETWEEN THE PLATES!!!


A capacitor is related to the charge on its plates and the voltage between its plates by

* Q and V can change each other but they can’t change C!!! *


Resistors + Simple Circuits


Resistance of a resistor is determined by its length and cross-sectional area: