Exam # 1 Study Guide Chapters 19-22Chapter 19Coulomb’s Law-F = k|q1||q2|/r2- Magnitude of force between two charges- If there are more than two charges, calculate the magnitude and direction of F for each pair and find the net force using vector additionPoint Charges-E = k|q|/r2- Direction of the field depends on the sign of the charge (away from + but towards - )- If there is more than one charge, use vector addition to find the net electric field- A point charge in an external electric field feels of a force F = qE (direction is dependent on whether the charge is + or -Electric Flux- ΦE = EA cos θ- Where θ is the angle between the electric field and the vector perpendicular to the area- There is no flux if A is parallel to the field - The total flux through any closed surface is given by Gauss’s Law: ΦE = qenc/є0Chapter 20Electric Potential-∆V = ∆U/q0-This is NOT a vector quantity PHYS 1302- The electric potential due to a point charge at a distance r away from the charge is V= kq/r (where ∞ is the point of zero potential)- The potential energy between charges separated by a distance r is U = kqq0/rElectric Field-|E| = |∆V/∆s- Points in the direction of decreasing potentialConservation of Energy-Ki + Ui = Kf + Uf or Ki − Kf = Uf − UiEquipotential Lines- Always perpendicular to electric line fields- Potential is the same everywhere on the equipotential surface or lineCapacitance-C = Q/V- If a dielectric material is inserted between the plates of a capacitor, the capacitance increases by a factor κ , which is different for different materials (if there is no dielectric material, κ = 1)Chapter 21Electromotive Force- EMF is the electric potential between the terminals of a batteryOhm’s Law and Power- V = IR- P = IV- P = V2/R or P = I2RCircuits- Know the rules for series vs parallel circuits and know Kirchoff’s rules (junction and loop)-q(t) = CV (t)- Charging RC circuits: At time t = 0, q(t) = 0 and V (t) = 0. At time t = ∞, q(t) = Q = CE and V (t) = E- Discharging RC circuits: At time t = 0, q(t) = Q = CE and V (t) = E. At time t = ∞, q(t) = 0 and V (t) = 0Chapter 22Right Hand Rule- Know the right hand rule - it is a great tool for determining magnetic force- Force is always perpendicular to both the magnetic field and the motion of the charge- If particle is negative, flip direction Magnetic Force-F = qvB sin θ (or F = ILB sin θ)-If a charge moves perpendicular to the magnetic field, the magnetic force causes the particle to move in a circle-Magnetic field lines are always closed loopsCurrent-Carrying Wires- Experience a force in external magnetic fields- Produce magnetic fields themselves- Long parallel wires with currents in the same direction experience attractive forces whilelong parallel wires with currents in opposite directions experience repulsive forces- Two parallel loops of current experience attractive forces if currents are in the same direction, and repulsive forces if the currents are in opposite directions Solenoids- A device in which a long wire is wrapped into very tightly spaced loops- Ideally, the field inside should be constant and directed along the axis of the solenoid while the outside field equals