1. A parallel-plate capacitor has circular plates of6.50cm radius and1.90mm separation. (a) Calculate the capacitance. (b) What charge will appear on the plates if a potential difference of120V is applied?2. A200pF capacitor is charged to a potential difference of70V, and the charging battery is disconnected. The capacitor is then connected in parallel with a second (initially uncharged) capacitor. If the potential difference across the first capacitor drops to46V, what is the capacitance of this second capacitor?3. A2.0F capacitor and a6.0F capacitor, are connected in parallel across a400V potential difference. Calculate the total energy stored in the capacitors.4. In the figure below,V= 9.0 V,C1=C2=32F andC3=C4=16F. What is the charge onC4?5. A coil is formed by winding250turns of insulated14gauge copper wire (diameter =1.6mm) in a single layer on a cylindrical form of radius12cm. What is the resistance of the coil? The resistivity of copper is1.6910-8m. Neglect the thickness of the insulation.6. A conducting wire has a1.5mm diameter, a 2.0 m length, and a70mresistance. What is the resistivity of the material?7. A wire with a resistance of10.0is drawn out through a die so that its new length istwiceits original length. Find the resistance of the longer wire, assuming that the resistivity and density of the material are unchanged.8. Two conductors are made of the same material and have the same length. ConductorAis a solid wire of diameter1.0mm. ConductorBis a hollow tube of outside diameter6.0mm and inside diameter3.0mm. What is the resistance ratioRA/RB, measured between their ends?9. A114V potential difference is applied to a space heater whose resistance is12when hot.10. In the figure below, the ideal batteries have emfs1=12V,2= 6.0 V, and the resistors have resistancesR1= 4.0andR2=7.0.11. In the figure below, circuit sectionABabsorbs energy at a rate of50W when currenti=1.5A through it is in the indicated direction. ResistanceR= 2.0.(a) What is the potential difference betweenAandB? Emf deviceXlacks internal resistance. (b) What is the emf of deviceX?12. What multiple of the time constantgives the time taken for an initially uncharged capacitor in anRCseries circuit to be charged to71.0%of its final charge?13. In the figure below, the ideal battery has emf=24V, the resistances areR1=25kandR2= 10 k, and the capacitor is uncharged.14. In the figure below,R1=R2=15.0, and the ideal battery has emf=6.0V. (a) What value ofR3maximizes the rate at which the battery supplies energy?(b) What is that maximum rate?

1. A piece of copper is made into a rod with a square cross section. The side of the square is 2.00 centimeters. The resistivity of copper is . The length of the rod is 5 meters and an unknown electric field is directed along the rod, creating a current of 12.0 amperes.A. What is the resistance of the rod?B. What is the potential difference across the rod?C. What is the magnitude of the electric field?D. How much energy is lost to heat in one hour?2. Look at the diagram below:

A. What is the equivalent capacitance of the circuit?B. What is the charge on each capacitor?C. What is the total energy stored within the capacitors?3. Look at the figure below: NOTE: 1k=1000 Ohms

A. What are the values of all the currents flowing within this circuit?B. What is the power supplied by the second battery? (V2)4. Look at the RC circuit below:

A. Immediately after switch 1 is closed and switch 2 is left open, what is the current through R1 and the charge on the capacitor (C1)?B. What is the charge on the capacitor after 100 ms?C. After a long time, what is the energy stored in the capacitor?D. Once the capacitor is fully charged, switch 1 is opened and switch 2 is closed. What is the magnitude of the current through the circuit containing only the resistor and the capacitor after 50 ms?5. Look at the image below:

A. Immediately after the switch is closed, what are the currents through each resistor?B. The switch has been closed for a long time, what are the currents through each resistor now?C. What is the final energy stored on the capacitor?