1. Using charge of one electron, determine how many it will take to total given charge.
3. Use Coulomb's law
4. Distance is reduced by 1/3, force is affected by inverse square.
5. Assume excess (net) charge will divide equally between the two pith balls.
6. (a) Use Coulomb's law and fundamental charge of electron and proton. (b) Look up mass of proton and electron and use law of universal gravitation. (c) Divide (b) into (a)(2.27 x 1039)
9. Remember one way to define the electric field is force/charge. Be careful with units - this charge is in microcoulombs.
11. (a) Use Newton's 2nd law. (b) Field equals force/charge; the charge here is that of an electron.
p 402
1. V = W/q; work divided by charge present. Watch your units.
2. Use same equation as #1, but solve for work. Charge in this case is total charge for the 13 minutes, potential is that of the battery. (290 J)
4. Use C = Q/V, watch units.
5. (a) Use reciprocal equation for total capacitance in series; shortcut for only 2 caps in series is CT = C1C2/(C1+C2) (1.50 microfarads) (b) in parallel, total is simply sum of capacitances of each cap.
6. In parallel, each cap will have same potential across it so Q = CV for each.
9. (a) Capacitance will be increased by a factor equal to the dielectric constant of the paraffin. (b) Use Q = CV (165 pF) (c) skip
10. (a) could be all series, all parallel, or combinations for 4 total. (b) to simplify combinations, find equivalent capacitance of two capacitors (series or parallel), then treat that as a single capacitance with the remaining capacitor. (Possible capacitances are 6, 2/3, 4, and 3 microfarads)