Exam Information In class next Friday, ~1 hr. 15 multiple-choice problems Half “conceptual,” half calculation Closed book, one page of notes One 8 ½” x 11” sheet of paper May contain whatever information you think might help Bring a calculator Cannot connect to internet or contain text book e.g. not phone, computer, iPad, etc.

Please be aware: Provided—If you something necessary missing, let me know Constants e.g. ε0, μ0, etc. Formulas not from course e.g. volume of a sphere Not provided—If you want them, put them on your note sheet Unit definitions e.g. V = J / C Formulas from course

What NOT to study Midterm Exam 2012

Topics NOT on the exam You should be familiar with the following material, but not exam questions will specifically test for knowledge of it Anything not in the requested reading, including the following material from lectures Electric energy density (18.8) Ammeters and Voltmeters (19.6) Temperature dependence of resistance (19.10) Earth’s magnetic field and cosmic rays (20.9) Applications of induction (21.7) Impedance in AC circuits (22.7) Transformers (22.9)

Topics NOT on the exam You should be familiar with the following material, but not exam questions will specifically test for knowledge of it These specific topics from lecture Dielectrics Real batteries Magnetic moment Hall effect Chapter 23 (lucky!)

Midterm Review Midterm Exam 2012

WARNING! This review is NOT comprehensive It should serve as a reminder of major topics covered by the course It will not review all topics covered Be sure to review all lecture slides, assigned reading, homework, and recitation notes

Charge and Electric Force Electric charge comes in two types: + and – Charges exert a force on other charges Likes repel, opposites attract Force is vector (obeys superposition) Magnitude given by Coulomb’s law: Directional (doesn’t change magnitude) Chapter 17

Electric Fields and Field Lines Electric field quantifies the “force potential” of one charge Divide out second charge Field lines represent electric field graphically Lines begin on + and end on – Chapter 17

Flux and Gauss’s Law Gauss’s law can help find electric field Useful for simple geometries Point, sphere, line, barrel, sheet, Relates net electric flux to enclosed charge Flux entering is negative, flux exiting is positive Electric Flux is defined as: Magnetic flux is similar Flux is a scalar quantity Chapter 17

Potential and Potential Energy Potential energy measures the energy required to move a charge to its present position Usually referenced from infinity Only net displacement along direction of force matters Potential (or voltage) quantifies “energy potential” of one charge Chapter 18

Equipotential Surfaces and Electric Field Lines Equipotential surfaces represent potentials graphically Equipotentials are 3D Connect points of same potential Largest positive magnitude near + Largest negative magnitude near – Equipotentials are everywhere perpendicular to electric field lines Chapter 18

Summary Vector Scalar 2-particle Force: (N) Potential Energy: (J)             1-particle             Electric Field: (N/C) Potential: (V)

Conductors and Insulators Conductors and Insulators (non-conductors): Conductors (metals) Charge moves around Excess charge is all on the surface E field inside is zero Entire object can be charged Insulators No conduction (movement) of charge Extra charge stays where it is placed

Polarization and Induction Electric fields can cause charges to align, causing material to polarize Occurs in both conductors and insulators Used to induce a net charge in a region or across an entire object

Magnetic Fields and Forces Created by moving charges Form loops from north to south Shape—wire, loop, solenoid, etc. Right-hand rule 1 Magnetic forces Perpendicular to field Right-hand rule 2 Particle, current wire, current loop Mass spectrometer, Bubble Chamber Torque

Right-Hand Rule Right-hand Rule 1 gives direction of Magnetic Field due to current Right-hand Rule 2 gives direction of Force on a moving positive charge Section 20.1

Magnetic Induction Faraday’s Law Lenz’s Law “A changing magnetic flux induces a voltage” Lenz’s Law “the magnetic field produced by an induced current always opposes any changes in the magnetic flux”

Resistors, Capacitors, and Inductors Series vs. Parallel Series—the same current Parallel—the same potential change across each component Resistors Ohm’s Law: Resistance depends on how resistor is constructed For resistors in series For resistors in parallel

Resistors, Capacitors, and Inductors Capacitance is defined as Capacitance depends on how capacitor is constructed For capacitors in series For capacitors in parallel

Resistors, Capacitors, and Inductors Inductance is defined as Inductance depends on how inductor is constructed For inductors in series For inductors in parallel

Circuits Current Kirchhoff’s Rules Loop Rule—the change in potential energy of a charge as it travels around a complete circuit loop must be zero Junction Rule—the amount of current entering a junction much be equal to the current leaving it

DC and AC circuits DC Circuits AC Circuits Voltage at source is constant RL circuits RC circuits AC Circuits Voltage at source oscillates I and V in AC circuits RMS, Average, Instantaneous LRC circuits Resonance