Calculating Charges

You solve a problem to find the charges on three objects. Your calculations lead you to conclude that the objects have charges of:

Q1 = 5 x 10-15 C

Q2 = 5 x 10-19 C

Q3 = 5 x 10-23 C

Are any of these results clearly incorrect?

  1. They're all wrong
  2. Q1 and Q3 are both wrong
  3. Q2 and Q3 are both wrong
  4. Q3 is wrong
  5. No - all of these answers are possible














Charge is quantized - it comes in integer multiples of the elementary charge
e = 1.60 x 10-19 C.

Q3 is definitely wrong - the charge is far too small. It represents a small fraction of e, which is impossible. The other two answers are fine, although Q2 is probably 3e, 4.8 x 10-19 C.

Note that quarks have fractional charge (a charge with a magnitude less than e), but the magnitudes are e/3 and 2e/3. In general we won't deal with quarks in this course.