1. 1 Mid-term review Charges and current. Coulomb’s Law. Electric field, flux, potential and Gauss’s Law. Passive circuit components.  Resistance and resistor, Ohm’s Law. Resistance as a function of temperature. Power dissipated through a resistor.  Capacitance and capacitor. Simple RC circuit, charge and discharge and the time constant, and energy and energy density (PE E and u E ) stored in a capacitor.  Self-inductance and inductor. Simple RL circuit, “charge” and “discharge” and the time constant, and energy and energy density (PE B and u B ) stored in an inductor. Power and battery model (emf + internal resistance). Circuit analysis, simple connections in series and in parallel and the Kirchhoff’s rules. Current generates magnet field: Biot-Savart Law. Magnet field flux and Ampere’s Law. Lorentz force law. Motion emf, Faraday’s Law of induction and Lentz Law. Mutual and self induction.

2. 2 Mid-term review 1.A circle made of conductor with radius R carries charge Q. A particle of mass m carrying charge -q is brought in along the center line from far away to a distance d away from the circle. What is the velocity and acceleration of this particle at this point? Y X Z Q R -q, m d

3. 3 Mid-term review

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5. 5 2.A 3 meter tungsten wire with a diameter of 20 μm is stretched in a multi-wire chamber and is connected to a positive high voltage power supply which provides a voltage V to the wire with respect to a far away grounded cage. The capacitance of this wire is 30 pF ( 1pF = 10- 12 F). To get an electric filed strength at middle of the wire and 1 mm away from the wire surface to be 10000 V/m, what is the supplied high voltage V? One can treat the wire as infinitely long when calculating the electric field in the middle of the wire. V r E

6. 6 Mid-term review 3.In the circuit shown here, at t = 0, the switch is closed. The resistor values are marked in the circuit. The capacitors all have C = 2μF. The battery has emf = 12V, and an internal resistance of 10Ω. (1kΩ=1000Ω, 1MΩ=1000kΩ). (a)Write the current through point B as a function of time. (b) What is potential at point A when t=3 second?

7. 7 Mid-term review