3. For the circuit shown in the figure, what is the current through resistor R,, R2. Ra? R3 (1800) 10.0 V - R2 15 V (60 0) R1 (340) 4. A Nichrome wire is 50 em long. The resistivity of Nichrome is 1.5 x 10-60m at the 20 "C. The potential difference between the ends of wire is 4.0 V and a current of 2.0 A is flowing through the wire. A. Find the resistance of this wire. B. Calculate the diameter of the wire. C. If the wire is heated from 20 "C to 70" C, calculate the new resistance of the wire that is produced by this change in the temperature (Temperature coefficient of resistivity a = 4 x 10-* ). 5. Consider a series RC circuit as in the figure for which R = 1.00 MQ, C = 5.00 mF, and AV = 30.0 V. Find (a) the time constant of the circuit and (b) the maximum charge on the capacitor after the switch is thrown closed. (c) Find the current in the resistor 10.0 s after the switch is closed. 6. A 10 MQ resistor is connected in series with a 1.0 #F capacitor. The capacitor has an initial charge of 5.0 uC and is discharged by closing the switch att = 0. (a) At what time will the charge be 0.50 uC? (b) What is the current at this time?