Millikan Oil Drop Experiment

by Jules Bruno
Was this helpful ?
Everyone. So here we're going to say that in 1897 JJ Thompson's Cathode ray to experiments led to discovery of the negative charge of electrons. But what we can say further is that Thompson was unable to determine how much negative charge and electron possesses. And it wasn't until 1913 where Robert Millikan and harvey fletcher discovered the fundamental charge of an electron. Now here we're going to talk about the Millikan oil drop experiment here, we're going to say that Millikan and fletcher used oil droplets, charged plates, gravity and X rays to determine the amount of charge. And here there are certain things that we need to remember. We have our atomizer. This is just the container used to disperse the individual oil droplets here in this drawing, we can say that this is our atomizer. And what we do here is we would basically drive this atomizer into this opening and basically squeeze on the nozzle And a smith of oil droplets will be sprayed within our apparatus. Next we need to realize that we have something called electric force. This is basically the attractive and repulsive forces between particles based on electric charges. Remember in chemistry, opposite charges attract, we're going to say same charges repel. Now, once we've stuck in this atomizer and basically dispersed our old droplets into the apparatus here we have our oil droplets, these little dots. What happens here is these oil droplets are going to fall through here. This plate. This plate here on top is are positively charged plate. Okay, now, going back to the experiment, the droplets, we say we're introduced to the atomizer, they go through the positive plate here. This is our X ray source. So it's basically going to zap our oil droplets. So the X ray source zaps our oil droplets to give them a negative charge. Here we have our microscope which basically looks at our charged oil droplet, which would be this little dot right here. So here, that's our charged oil droplets. And this blue plate here would just be our negatively charged plate. Now, this box here would be our volt meter which will read the the voltage or charge that could be produced within this experiment. Now here, if we turn on the power of the charge plates, it's gonna create an electric field. And what's important about this electric field is we're going to say that if the voltage is turned up and it becomes greater than the force of gravity, that the drop of itself will rise. But if the voltage is not high enough and it's less than the force of gravity, then the old droplet will fall. What we have to do here is we have to apply the right amount of voltage that will help. If we can do it, help the drop it be suspended in air. And if we could suspend that droplet in air between our positive and negative plates, it's through the suspension that we can figure out the charge of our electron. And that's what they were able to do with this experiment. See through the suspension of the oil dropping, the charge of an electron was determined to be negative 1. times 10 to the -19 columns columns representing charge. Okay, so just realize that when it came to the Millikan oil drop experiment, it helped to further the experiment of Thompson. It helped us to figure out the amount of negative charge on any given electron.