A 650 x 10-4 F capacitor stores 24 x 10-3 of charge. What is the potential difference between the plates?
0.0016 V
0.089 V
0.37 V
2.7 V

The radioactive isotope of lead, pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.3 hours. if 1 gram of this isotope is present initially, how long will it take for 80% of the lead to decay? (round your answer to two decimal places.)