00:00:12.380 --> 00:00:14.740 The capacitor is the essential component of any 00:00:14.750 --> 00:00:15.750 circuit design. 00:00:15.750 --> 00:00:20.590 And in fact, after the resistor, it is the second most used passive component in the 00:00:20.590 --> 00:00:21.590 circuits. 00:00:21.590 --> 00:00:26.340 Now, these capacitors are available in various size and shapes. 00:00:26.340 --> 00:00:30.630 But the basic function of any capacitor is to store the electrical energy. 00:00:30.630 --> 00:00:36.750 So, now in this video, let's understand how does this capacitor work and how the energy is 00:00:36.750 --> 00:00:38.710 stored across this capacitor. 00:00:38.710 --> 00:00:44.760 Now, this capacitor consists of two conductive plates which are separated by a dielectric 00:00:44.760 --> 00:00:45.760 material. 00:00:45.760 --> 00:00:51.790 Now, this dielectric material is the insulating material and it opposes the flow of current. 00:00:51.790 --> 00:00:57.489 So, now let's understand when we apply the voltage to this capacitor then how the energy 00:00:57.489 --> 00:00:59.369 is stored across this capacitor. 00:00:59.369 --> 00:01:04.170 Now, before the application of voltage, the two conducting plates of this capacitor are 00:01:04.170 --> 00:01:05.960 electrically neutral. 00:01:05.960 --> 00:01:10.220 It means that it has the equal amount of positive as well as the negative charge. 00:01:10.220 --> 00:01:16.360 But once the voltage is applied to this capacitor, then from the top plate the electrons or the 00:01:16.360 --> 00:01:22.210 negative charge is attracted towards the positive terminal of this battery. 00:01:22.210 --> 00:01:26.990 And through the negative terminal of the battery, the electrons are pushed towards the bottom 00:01:26.990 --> 00:01:28.370 plate of this capacitor. 00:01:28.370 --> 00:01:33.850 Now, because of the dielectric material between the two plates electrons which are collected 00:01:33.850 --> 00:01:38.540 at the bottom plate of this capacitor are not able to cross this barrier. 00:01:38.540 --> 00:01:42.960 And because of that, you will observe that over the period of time the electrons will 00:01:42.960 --> 00:01:46.120 get accumulated at the bottom plate of this capacitor. 00:01:46.120 --> 00:01:52.230 So, over the period of time, the top plate will have a shortage of electrons, while the 00:01:52.230 --> 00:01:54.780 bottom plate will have excessive electrons. 00:01:54.780 --> 00:02:00.180 Or we can say that the top plate will get positively charged, while the bottom plate 00:02:00.180 --> 00:02:02.460 will get negatively charged. 00:02:02.460 --> 00:02:06.790 And because of the charged particles, the potential difference will get developed across 00:02:06.790 --> 00:02:08.020 the two plates. 00:02:08.020 --> 00:02:13.290 Now, the building of charges across the two plates will continue till the point the potential 00:02:13.290 --> 00:02:17.940 difference that is developed across the two plates is equal to the supplied voltage. 00:02:17.940 --> 00:02:22.959 Now, because of this potential difference, the electric field will get developed across 00:02:22.959 --> 00:02:24.709 00:02:24.709 --> 00:02:30.060 And this developed electric field is directly proportional to the potential difference and 00:02:30.060 --> 00:02:33.670 it is inversely proportional to the distance between the two plates. 00:02:33.670 --> 00:02:38.760 So, smaller the distance between the two plates, the stronger will be the electric field. 00:02:38.760 --> 00:02:44.450 So, in this way, when we apply the voltage to the capacitor, then the charges are developed 00:02:44.450 --> 00:02:49.020 across the two plates of this capacitor and because of the development of the charge, 00:02:49.020 --> 00:02:52.250 the electric field is developed between the two plates. 00:02:52.250 --> 00:02:57.970 So, in this way, the capacitor stores the energy in form of this electric field. 00:02:57.970 --> 00:03:03.730 Now even if we remove this voltage source, then also the charges that are developed across 00:03:03.730 --> 00:03:05.910 the two plates will remain as it is. 00:03:05.910 --> 00:03:11.870 So, unless we apply the conductive path to this capacitor, the charges that are developed 00:03:11.870 --> 00:03:14.120 across the two plates will remain as it is. 00:03:14.120 --> 00:03:19.310 So, as you can see over here, the conductive path is connected between the two terminals 00:03:19.310 --> 00:03:20.540 of this capacitor. 00:03:20.540 --> 00:03:25.209 And load in the form of the bulb is connected to this conductive path. 00:03:25.209 --> 00:03:31.200 So, now whenever we turn on this switch at that time, the electrons from the bottom plate 00:03:31.200 --> 00:03:35.180 will get attracted towards the top plate. 00:03:35.180 --> 00:03:40.349 And in this way, you will see the transfer of charge or flow of current through this 00:03:40.349 --> 00:03:41.349 conductive path. 00:03:41.349 --> 00:03:46.700 So, now because of the flow of current, you will see that the bulb will grow. 00:03:46.700 --> 00:03:50.370 And in this way, the current will flow through this conductive path. 00:03:50.370 --> 00:03:55.330 And this procedure will continue till both the plates will become electrically neutral. 00:03:55.330 --> 00:04:00.670 So, over the period of time, you will observe that both plates will become electrically 00:04:00.670 --> 00:04:02.010 neutral. 00:04:02.010 --> 00:04:06.090 And there will not be any flow of electrons through this conductive path. 00:04:06.090 --> 00:04:09.519 And because of that, the bulb will again turn off. 00:04:09.519 --> 00:04:15.590 So, in this way, the charge that was developed across the capacitor has been discharged through 00:04:15.590 --> 00:04:17.470 00:04:17.470 --> 00:04:21.650 And this phenomenon can be known as the discharging of the capacitor. 00:04:21.650 --> 00:04:28.310 Now, the ability of the capacitor to store the charge is known as the capacitance. 00:04:28.310 --> 00:04:35.000 And it is represented as the charge that is developed across the capacitor per unit voltage. 00:04:35.000 --> 00:04:38.139 And generally, it is denoted by the unit of Farad. 00:04:38.139 --> 00:04:43.150 Now, this farad is a very big unit and usually, it is not used to define the capacitance. 00:04:43.150 --> 00:04:50.169 Rather very small units like mF, uF and pF are used to define the capacitance. 00:04:50.169 --> 00:04:55.939 So, now for the given capacitance if you want to store the more charge across the capacitor 00:04:55.939 --> 00:04:59.779 then you need to apply the more voltage across that capacitor. 00:04:59.779 --> 00:05:04.710 Or for the given voltage suppose if you want to store the more charge across the capacitor, 00:05:04.710 --> 00:05:08.900 then you need to select the capacitor in a such a way that it has a large capacitance. 00:05:08.900 --> 00:05:14.819 So, as you can see over here, by changing the applied voltage we change the amount of 00:05:14.819 --> 00:05:18.030 charge that is stored across the capacitor. 00:05:18.030 --> 00:05:21.129 But here we can not increase the voltage indefinitely. 00:05:21.129 --> 00:05:26.300 So, for every capacitor, you will find that the maximum voltage rating has been defined. 00:05:26.300 --> 00:05:31.400 So, the voltage that is applied across the capacitor should be less than that maximum 00:05:31.400 --> 00:05:32.400 rating. 00:05:32.400 --> 00:05:36.830 So, if the applied voltage is greater than the maximum rated voltage, in that case, you 00:05:36.830 --> 00:05:39.300 will see the dielectric breakdown in the capacitor. 00:05:39.300 --> 00:05:44.159 So, now let's see the factors which affect the capacitance of this capacitor. 00:05:44.159 --> 00:05:49.449 So, there are three factors which affect the capacitance of this capacitor. 00:05:49.449 --> 00:05:53.900 The first is the area of the plates. then the second factor is the distance between 00:05:53.900 --> 00:05:55.879 the two plates of this capacitor. 00:05:55.879 --> 00:06:01.190 And the third factor is the permittivity of the dielectric material. 00:06:01.190 --> 00:06:05.629 And the relation between three can be given by this expression. 00:06:05.629 --> 00:06:07.990 That is C is equal to ε*A/d. 00:06:07.990 --> 00:06:13.650 So, as you can see over here, the capacitance of this capacitor is directly proportional 00:06:13.650 --> 00:06:19.080 to the area of the plate as well as the permittivity of this dielectric material. 00:06:19.080 --> 00:06:22.389 And it is inversely proportional to the distance between the plates. 00:06:22.389 --> 00:06:26.939 So, now let's see, how these factors can affect 00:06:26.939 --> 00:06:30.360 So, the first factor is the area of these plates. 00:06:30.360 --> 00:06:35.939 So, as the area of the plates increases, the amount of charge that can be stored across 00:06:35.939 --> 00:06:38.129 the plates will also increase. 00:06:38.129 --> 00:06:42.430 And in a way, we can say that the capacitance of the capacitor will increase. 00:06:42.430 --> 00:06:48.119 Now, the second factor which affects the capacitance is the distance between the two plates. 00:06:48.119 --> 00:06:54.240 So, now as the distance between the two plates reduces, the electric field that is developed 00:06:54.240 --> 00:06:57.699 across the two plates will also increase. 00:06:57.699 --> 00:07:01.180 Because it is inversely proportional to the electric field. 00:07:01.180 --> 00:07:06.179 And as this electric field increases, the charge that can be stored across the capacitor 00:07:06.179 --> 00:07:07.469 will also increase. 00:07:07.469 --> 00:07:13.619 So, the third factor which affects the capacitance is the permittivity of the dielectric material. 00:07:13.619 --> 00:07:19.429 Now, this permittivity can be defined as the product of absolute permittivity and the relative 00:07:19.429 --> 00:07:20.429 permittivity. 00:07:20.429 --> 00:07:24.909 Where this relative permittivity is also known as the dielectric constant of the material. 00:07:24.909 --> 00:07:30.189 So, because of this dielectric material, the capacitance of the capacitor will increase. 00:07:30.189 --> 00:07:36.000 So, now let's understand how this dielectric material affects the capacitance of the capacitor. 00:07:36.000 --> 00:07:41.129 Now, like I said before, this dielectric material is the insulating material. 00:07:41.129 --> 00:07:44.249 So, it will not allow the flow of current. 00:07:44.249 --> 00:07:47.849 But this dielectric material has polar molecules. 00:07:47.849 --> 00:07:52.800 It means that whenever there is no electric field, in that case, these molecules are aligned 00:07:52.800 --> 00:07:54.220 randomly. 00:07:54.220 --> 00:07:59.249 But whenever the external electric field is applied, in that case, these molecules aligned 00:07:59.249 --> 00:08:01.830 themselves according to the electric field. 00:08:01.830 --> 00:08:07.259 So, at the top edge of the dielectric material, if you see, you will find the negative charges. 00:08:07.259 --> 00:08:12.459 While at the bottom end of this dielectric material you will find the positive charges. 00:08:12.459 --> 00:08:17.830 Now, these charges develop its own electric field, which opposes the electric field that 00:08:17.830 --> 00:08:19.740 is generated by the capacitor. 00:08:19.740 --> 00:08:24.479 effective electric field of the capacitor 00:08:24.479 --> 00:08:25.949 will reduce. 00:08:25.949 --> 00:08:30.089 And in a way, we can say that the potential difference that is generated across the two 00:08:30.089 --> 00:08:35.300 plates will also reduce, provided the charges that are developed across the two plates are 00:08:35.300 --> 00:08:36.300 constant. 00:08:36.300 --> 00:08:41.580 So, in that case, to increase the potential we require the more amount of charge across 00:08:41.580 --> 00:08:42.580 00:08:42.580 --> 00:08:47.640 So, in a way, we can say that, because of the introduction of this dielectric material, 00:08:47.640 --> 00:08:50.210 the capacitor can more amount of charge. 00:08:50.210 --> 00:08:54.990 Or we can say that the capacitance of the capacitor will increase. 00:08:54.990 --> 00:08:59.470 So, these are the three factors which affect 00:08:59.470 --> 00:09:06.700 So, I hope in this video, you understood how does the capacitor works and which are the 00:09:06.700 --> 00:09:09.120 factors which affect the capacitance of the 00:09:09.120 --> 00:09:14.700 So, if you have any question or suggestion, do let me know in the comment section below. 00:09:14.700 --> 00:09:17.302 If you like this video, hit the like button and subscribe to the channel for more such 00:09:17.302 --> 00:09:17.802 videos.
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