Exam 1 Review Phys 222 Supplemental Instruction Do you know all the - PowerPoint PPT Presentation

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

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

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

Dipoles (dipole moment)  𝒒 = |𝑅|𝒆  !! Notice: Dipole moment points from negative to positive….opposite of the direction E points

Dipole Moment and Torque  𝝊 = 𝒒 × 𝑭  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

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.

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

Cylinder with charge 5C

Capacitance and Energy 𝑅 2 1 2 𝐷𝑊 2 = 1  𝑉 = 2𝐷 = 2 𝑅𝑊  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

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

Hodgepodge OF RELEVANT QUESTIONS