Thomson discovered the value of mass per charge (e/m). However, the value of the electron charge is not yet known. Millikan was one of the scientists who studied the charge of electrons. He designed a device that could be used to calculate the charge of an electron. The apparatus he designed would later become known as the oil drop experiment.
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LearningTranscript
00:00Between 1909 and 1913, Robert Millikan conducted an experiment.
00:10Today, the experiment is known as the oil drop experiment.
00:16Through the oil drop experiment, Millikan succeeded in obtaining the electrical charge of electrons.
00:25This discovery led Millikan to receive the Nobel Prize in Physics in 1923.
00:36To understand the oil drop experiment, here is the shape of the apparatus.
00:50A closed tube.
00:53This tube is indeed closed, but inside this tube there is still some air.
00:58So, this tube is not a vacuum tube.
01:03This tube is closed so that the air in the tube is the same particle.
01:09Thus the number of air particles is the same, the air density is the same, the air viscosity is the same, and other air properties are the same.
01:18It's a kind of control variable.
01:25Atomizer.
01:28This may be a term that is quite foreign to most of us.
01:32It looks like you have a perfume bottle.
01:35A perfume bottle containing liquid alcohol.
01:41If you spray the perfume on the palm of your hand, you will not see the liquid in the air, but the skin of your palm will look wet.
01:52Well, the perfume bottle is an atomizer.
01:55A tool that converts liquids into substances in very small sizes, as small as atoms.
02:03In this experiment, the atomizer will spray oil in dust sizes, even smaller than that.
02:14Microscope.
02:17We often use microscopes in experiments at school.
02:21This tool is not something strange.
02:26Through a microscope, we can enlarge the view of objects at a certain scale.
02:31We can see the particles clearly and can measure the distance traveled by the particles.
02:42X-ray.
02:45This tool can emit electromagnetic waves.
02:50Electromagnetic waves from X-ray can ionize air particles into ions.
03:01Light.
03:04I'm sure we all know this tool well.
03:09As we know, in a closed room it will look dark.
03:13With the lights there, we can see things inside more clearly.
03:23Next is the DC voltage source.
03:27A DC voltage source can provide an electric charge on parallel plates installed in a closed tube.
03:34In this way, an electric voltage will arise between the plates.
03:41Note the top plate.
03:44There is a small hole there.
03:48This hole allows oil in the size of dust to pass through.
03:54These are some of the components used by Millikan in conducting oil drop experiments.
04:01We will use this tool in the next series.
04:06Thank you for watching this video.
04:09And, don't forget to watch the next video.