Good Luck! Exam 1 Review Phys 222 – Supplemental Instruction

Do you know all the following?

Electric Charge Coulomb’s law Charged objects’ behavior Conductors, Insulators, Polarization Electric Charge Interaction Electric field, field lines Dipoles, dipole moment Flux Integral Representation Gaussian Representation Applying Gaussian surfaces to objects

Electric Potential (vs) Electric Potential Energy Equipotential Diagrams Calculating potential at various points Movement of charge in the presence of a potential. Relation to other types of energy

Capacitance How various changes affect capacitance What are their uses Connections in circuits Parallel vs series Equivalent capacitance Dielectric additions Current Relation to other concepts Resistance Connections, much like capacitors

Here we go! Lots of test problems with tips sprinkled in

D Spring 2011

C SP 12

Forces and energy: Depend on recipient and emanating charge. Emanating charge -- Q Electric Force Electric Potential Energy Divide by q Electric Field Electric Potential Difference (voltage) Field descriptions: Do not depend on recipient particle/charge. Recipient charge -- q

E W = change in U, = -q(Delta)U Sp 12

B Sp13

Field lines! Electric field lines go from + to - Electric field lines end at negative charges. Line density indicates field strength

D SP14

D Sp 2011

D Set gravity = electric (qE) Sp 2011

Dipoles 𝒑=|𝑄|𝒅 (dipole moment) !! Notice: Dipole moment points from negative to positive….opposite of the direction E points

E T = p cross E SP 12

Dipole Moment and Torque 𝝉 = 𝒑×𝑬 Know right hand rule for cross products! This will help you eliminate wrong choices Note that E is not the E produced by dipole. E is external Torque minimums and maximums Max when p perpendicular to E U = -p ⋅ E

C Cylindrical Symmetry: A = 2pi*R/L Sp13

Steps in solving GL Problems Draw a picture. Pick a good Gaussian surface. Symmetry! Write expression of integral flux notation. (if E parallel to A then, EA) Write expression for Gauss’s Law involving enclosed charge. Set the expressions equal and eliminate variables to solve.

A SP 12

Relating Charge (Q) to field (E) Is the charge distribution discrete (set of charges)? No No Is there symmetry? Was it solved in class? No Yes Yes Yes Use Gauss’s law to relate charge enclosed to the field at any point. Use a formula such as for an infinite plane or ring of charge. Solve for the relation by setting up an integral version of Coulomb’s law with dq and dr Use Coulomb's law on each and add results using vector addition.

Cylinder with charge 5C

Capacitance and Energy 𝑈= 1 2 𝐶 𝑉 2 = 𝑄 2 2𝐶 = 1 2 𝑄𝑉 Wait, why are there three equations? If asked to calculate U, just use the one that has known variables If asked what happens to U when you double, half, etc. If the capacitors are stand alone, use Q^2 equation If the capacitors are connected to constant voltage use V^2 equation

E Sp2011

Combining components Parallel Series Resistors Capacitors Addition T = X1 + X2 +… Inverse Addition 1/T = 1/X1 + 1/X2 +… Parallel Inverse Addition 1/T = 1/X1 + 1/X2 +… Addition T = X1 + X2 +… Series

Hodgepodge Of relevant questions

C F12

A F12

B F12

A SP14

A SP14

C F12