1. Good Luck! Exam 1 Review Phys 222 – Supplemental Instruction

2. Do you know all the following?

3. 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

4. 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

5. 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

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

7. D
Spring 2011

8. C
SP 12

9. 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

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

11. B
Sp13

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

13. D
SP14

14. D
Sp 2011

15. D
Set gravity = electric (qE)
Sp 2011

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

17. E
T = p cross E
SP 12

18. 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

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

20. 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.

21. A
SP 12

22. 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.

23. Cylinder with charge 5C

24. 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

25. E
Sp2011

26. 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

27. Hodgepodge
Of relevant questions

28. C
F12

29. A
F12

30. B
F12

31. A
SP14

32. A
SP14

33. C
F12