1) A series RC circuit, which is made from a battery, a switch, a resistor, and a 4.0-µF capacitor, has a time constant of 8.0 ms. If an additional 6.0-µF is added in series to the 4.0 µF capacitor, what is the resulting time constant?
2) A copper wire of length 26.0 cm is in a magnetic field of 0.390 T. If it has a mass of 13.0 g, what is the minimum current through the wire that would cause a magnetic force equal to its weight?