One could easily determine a single bb's mass by simply weighing it or by weighing 100 BBs and dividing the mass by 100. Why couldn't Robert Millikan use this procedure to measure the charge of an electron?
Thanks:)
How would he have counted electrons?
Robert Millikan couldn't use the same procedure to measure the charge of an electron because the charge of a single electron is extremely small. The charge of an electron is approximately 1.6 x 10^-19 coulombs.
If Millikan were to directly measure the charge of a single electron by weighing it, the resulting mass difference would be extremely difficult to detect. The weight of a single electron is so minute that it falls below the resolution of traditional weighing scales. Therefore, weighing a single electron to determine its charge is not a viable option.
To overcome this challenge, Millikan devised an experiment known as the oil drop experiment. He used an apparatus where electrically charged oil droplets suspended in a chamber were subjected to an electric field. By carefully adjusting the electric field strength, he could observe how the droplets moved and ultimately determine the charge of the electron.
In the experiment, Millikan measured and compared the resulting motion of the oil drops when they were positively or negatively charged. The measurements allowed him to accurately calculate the charge of a single electron.
Therefore, while weighing objects like BBs is a simple and direct method to determine their mass, the charge of an electron is too small to be measured through conventional weighing techniques.