Question

Millikan received the 1923 Nobel Prize in Physics for the oil drop experiment that was completed in 1910 about 100 years ago when knowledge of the atomic structure was not clear.

(a) what were the two main conclusions of the experiment that were worthy of a Nobel Prize?

(b) It has been reported that Millikan “cherry-picked” his experimental data. What are your thoughts on his treatment of the data – did he commit scientific misconduct?

(c) Why was oil used in these experiments?

(d) Why was it necessary to determine the terminal velocity of an oil drop?

(e) Assume a spherical drop of oil has r_o=824 kg/m³ ; the air has r_a=1.293 kg/m³ ; h=1.81x10^-5

Answer 1

a) "measuring the charge of the electron" ​and "verifying Einstein's prediction of the relationship between light frequency and electron energy in the photoelectric effect, a phenomenon in which electrons are emitted from matter after the absorption of energy from electromagnetic radiation such as x-rays or visible light."

b) The problem came much later when people started looking at the results a little more closely. So the first thing to come up was, wait, you seem to have thrown out a lot of outliers, dear Millikan. And the truth was that Millikan did throw out a lot of data saying, well, these things simply weren’t fully analyzed that related to charged particles that may not have had as close to the center of values as some of the other experiments.

So had he included all of the data he took in his initial publication, his error would’ve been higher and he still would’ve been within 2 percent of the actual value – sorry, he still would’ve had about 2 percent error in his results. But he didn’t want to leave that much wiggle room for detractors so he only published the best. So he cherry-picked the evidence.the other thing that was pointed out was not only did he cherry pick the data but then there was this problem over the following years that as people recreated his experiment did similar – did experiments that yielded different ways of getting at the charge of the electron – people kept coming up with higher values but no one was willing to step forward and say, hey, my value’s like 2 percent higher than his value or half a percent higher, as the case may have been.

c) Millikan sprayed charged oil droplets and allowed them to fall until they reached terminal velocity. Using their terminal velocity, he determined the mass of the oil droplets and was able to use the mass to determine the force of gravity acting on the droplets to pull them down.

d) Using their terminal velocity, he determined the mass of the oil droplets and was able to use the mass to determine the force of gravity acting on the droplets to pull them down.

e)