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26. Capacitors & Dielectrics

Dielectric Breakdown


Dielectric Breakdown

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Hey, guys, In this video, we're gonna be talking about a process known as Di Electric breakdown. Let's get to it. We know that die electrics or insulate er's and insulators charges can't move right. Well, ideally, charges can't move in reality if you motivate them enough. If you provide, for instance, large enough voltage, they will move across an insulate er, okay, it's very difficult, and it doesn't occur commonly, but it can occur. One such instance of this is a process known as di electric breakdown. Okay, just like the dialectic Constant Kappa is a fundamental quality of a die electric. We have a second fundamental quality called the dye electric strength, and what the dye electric strength is is It's the maximum electric field supported within a die electric before breakdown occurs. So if you go past that maximum electric field past that die electric strength breakdown occurs in di electric breakdown. What we get is we get electrons jumping from Adam toe Adam. Electrons can't exist freely within an insulate er like the cannon, the conductor, so all they could do is move from one atom to another. When they reach other Adam, they sort of knock off the electron that goes to another Adam that knocks off an electron, goes to another Adam, etcetera. And eventually the electrons cross the insulate er like so they sort of just jump from Adam toe Adam until they crossed the insulate. Er, okay. A very common example of die electric breakdown is lightning in a thunderstorm. We have some sort of thundercloud that through a process that we don't really know about charges separate within this thundercloud, we're going to get an accumulation off positive charges near the top of the thundercloud and negative charges near the bottom of the thundercloud on the ground. This is gonna pull positive charges near the surface of the ground. And this separation of charges right here is gonna act as a capacitor where the air filling this space between is going to be our die electric. And eventually, if the charge separation becomes large enough, the electric field becomes strong enough. Toe pass. The dye electric strength breakdown occurs, and we get lightning. Okay, let's do a quick example of this. Ah, parallel plate capacitor is filled with air and connected to a power source of volts. What is the closest you can put the plates together. If di electric breakdown of air occurs at an electric field of three times 10 to the six volts Premier, so three times 10 to the six volts per meter is the dialectic strength of air. Remember for air where always going to treat the dye electric constant as one. Okay, so the electric field, right, Max is three times 10 to the six volts per meter. This is the di electric strength. Well, within a parallel plate capacitor, the electric field is always going to be the voltage over the distance. Okay, So if we want to know the closest distance, all we have to do is multiply this distance up and divide this electric field over. Okay, so the distance is gonna be V over E max. Right? And the larger the electric field is the small of the distance. That's why we have the closest distance, right? The smallest distance for the largest electric field. This is gonna be 100 volts over three times 10 to the six, which is gonna be about times 10 to the negative. Four meters. Okay, 0.33 times since the negative 4 m. That is our answer. All right, this wraps up our discussion on die electric breakdown. Thanks for watching.