Question

Question:
Based on Millikan's Oil Drop Experiment, what can you conclude about the existence of a smallest unit of electric charge, of which other charges are multiples? Include a diagram of Millikan's original apparatus.

So i found lots of great websites, so please don't google Millikan and post a webpage. Here's a simplistic version of what I've got:

Description of the experiment...As more and more trials were done, it became evident that all of the droplets contained charges that were multiples of a smallest value. Millikan correctly concluded that this must be the value on an electron, and therefore the value of the elementary charge, 1.602 × 10-19 C.

Any other things I can add about his conclusion?
Thankyou.Rach.

Answer 1

Your description pretty much says it all, as far as the conclusion is concerned, and how it was arrived at. What he measured was the field necessary to keep the oil drops suspended between parallel plates. When it was motionless, the electric force, F = Q E, equaled the weight. He also had to figure out the weight of the drop, which he obtained from a fluid mechanical formula (Stokes' Law) by measuring the terminal velcoity as it fell.

Stokes' law is actually an approximation; a better version is called Oseen's Law