hello everyone welcome back to my youtube channel trouble free in today's video we are going to get started with the new playlist that is basic electrical engineering which is in short called as b double e and in some colleges they also call it as b triple as well so i used to have this subject in my second year first semester so when i have the subject i was like why why why do we have the subject and why they have included this for cse students so i did not like so much but still you know we have to since they have included we have to clear but it was some a bit difficulty to many of my friends so and even so many out also outside also so many people will say bw is heartbeat ripley's heart so that is why i just want to make it easier for you i'll try to simplify it for you in my own way and make sure that you will be writing well in the exam okay so in this video chapter one which is dc circuits we are going to learn basic uh electrical circuit elements so we have three elements so what are those three elements we will be learning in this video so those three elements first of all you know what is dc right dc ac dc is nothing but direct current ac means alternating current so dc is direct current and in this we have three elements three circuital elements we are having resistance inductance capacitance resistance is denoted by r inductance by l and capacitance by c okay now let us see about each of them first resistance resistance is nothing but it is a property of a conductor or you can take any material also but that has to be a conductor what do you mean by a conductor anything which allows the passage of electricity you know conductor semiconductors insulators right insulator will not at all of electricity semiconductors will partially allow and conductors they will allow the passage of the electricity through them okay so it is nothing but it is a property of a conductor which opposes the flow of current or electrons through it see in some books i have seen it as current in some books i have seen it as electrons so simply when a current is passing in a conductor okay the flow of that current or electrons will be opposed with the help of a resistance okay so usually uh resistance this is a symbol before symbol unity the unit of resistance is ohms and it is denoted in this way and the symbol is we will be having like this speed breakers okay so this is resistance and the current p is nothing but the potential difference okay next what is the formula to calculate the resistance then you know from ohm's law v is equal to ir so what is ohm's law i'll explain you basically ohm's law is nothing but potential difference across the conductor will be directly proportional to the con current flowing through it and when you remove this proportionality you will be getting the constant which is nothing but the resistance okay so about ohm's law and about the working problems some example problems of ohm's law i'll do it separately but for time being you just remember ohm's law is nothing but v is equal to ir you already learned about in your engineering in your 10th grade also for me in narendra i guess i learnt it in 7th or eighth grade i don't even know what is conductor what is resistance nothing i know in that age but okay so when you send this i over to this side it becomes divided by and r is equal to v by i okay and we also have another formula so when you are taking a conductor so if you are assuming a conductor then r is directly proportional to length length of the conductor resistance is directly proportional to the length of the conductor and it is inversely proportional to the area of cross section of the conductor got it so from both one and two equations what you can say by combining both one and two you can say that r is directly proportional to l by a right so whenever you remove the proportionality whenever you are making it as is equal to you will be getting a constant right so that constant is nothing but rho here so r is equal to rho into l by a where rho is called as the resistivity and the unit of rho is ohm meters okay so r is directly proportional to the length of the conductor and it is inversely proportional to the area of cross section of the conductor so if you are combining these two equations you will be getting a r is directly proportional to l by a and on removing this proportionality you will be getting the constant that constant is nothing but the resistivity okay and we have another formula also basically this formula is to calculate the power okay so power formula is v into i in all the three cases in case of capacitance in case of inductance also the formula for power is p is equal to v into i now what is v i r so v is equal to i r from ohm's law and what is i current as it is you're keeping it i r into i i square r p is equal to i square r so when you're given current and resistance you can find out power in this way okay so for everything for resistance for inductance for capacitance for everything in the exam if you are asked to explain about the electrical circuit elements first you have to write the definition okay next unit symbol and fourth is formula fifth is power equation and sixth phasor diagram okay all these things six things you have to write for both for each resistance inductance and capacitance in the exam if you are asked this question ok next phaser diagram for resistance so the place was not enough in the previous page that is why i have drawn it here see voltage and i both will overlap with each other sorry potential difference and the current both will overlap with with each other okay no lag or no lead theta is equal to 0 degrees no lag what is lag what is lead you will understand next in the inductance and capacitance you will understand what do you mean by lag and what do you mean by lead okay now second is second circular element is inductance inductance is usually represented with the symbol l okay so what do you mean by inductance the property the property of a conductor which opposes any change in the magnitude or direction of current passing through the material don't get confused see whenever you are confused with the definition come from the last come in the reverse direction if then also if you are not able to understand then nobody can do anything so current passing through the material any changes which are happening to the magnitude or direction of the current passing through the material see current is a vector quantity or a scalar quantity okay keeping that aside basically uh magnitude or direction in terms of magnitude or in terms of direction in terms of magnitude in the sense suppose if the value of current is 3 amperes and it has changed to 6 amperes the value has changed right this is change in magnitude change in direction is nothing but if the current is flowing in this direction suddenly it got changed to in this direction or it got changed to this direction whichever so if the direction or the magnitude of current is changing then that changes should not happen who is responsible for that who will take care of that conductor the conductor will oppose i mean sorry sorry sorry inductance so inductance is a property which will oppose the changes which are happening in the conductor change is related to what current it could be in the magnitude wise or it could be in direction wise so these two changes will be opposed with the help of the inductance property okay done next what is the unit hand rate is denoted by h and symbol is like this your coil okay next v is equal to l into d i by dt this is the formula we have so for inductance next power power is equal to vi you already know that what is v here l into d i by dt into i so p is equal to you are bringing this i over this side l i d i by dt d i by dt is nothing but the change in current so here as we said changes in the current so that change in current is di by dt okay and the unit of current power is what so we have written it as what and here also you can write v like voltage but if i write v again you will get confused right again one more v so i have not written now let us go to the phasor diagram so in phasor diagram this is the potential difference and this is the current okay potential difference current now the angle between the current and the potential difference is 90 degrees so we have written theta is equal to 90 degrees now which is leading which is lagging leading in a sense which is above which is up see leading means what lagging means what it has a lot of lot of physics theory involved in it but uh for time being i'm telling you which is on the top voltage is on the top right so volt from here to here 90 degrees and which is in the top of 90 degrees voltage so that is why voltage is leading the current by 90 degrees got it voltage is leading the current by 90 degrees this is about the inductance phasor diagram simple inductance is nothing but it is a property of the conductor which will oppose the changes which are happening to the magnitude or direction of the current in the conductor got it and unit is henry and the symbol is this coil kind of thing and the formula for power and phasor diagram all now let us move to the next thing that is the capacitance so capacitance also simple let me check if i have missed any points in inductance no now let us check capacitance it is a property of material to store electric charge within it simple it is the property of the material to store the electric charge within it and the unit of capacitance is ferret f a r a d farad it is denoted by f okay and the symbol is this one see you don't get confused with the symbol of battery battery will have one line big and one line small this is battery but capacitance two lines both positive and negative terminals will be equal in length okay that is the difference between the capacitor and the battery okay don't get confused so this is the uh this is the symbol of capacitance next formula c is equal to q by v or we have other formula like i is equal to c b c d v c by d t or see if you're getting confused between inductance and capacitance simple their voltage will play here current will play so here we have i is equal to c into dvc by dt right what was our formula there in inductance just reverse the terms i will become v c is l d i by d t right so you're just replacing the terms that's all nothing current and voltage are being replaced any one you remember and you replace the things okay next power is equal to v i same so in v i you know i here so v into c d v c by d t we say dvc by dt what's power okay next the phasor diagram for capacitance so basically for capacitance phasor diagram will be in this way voltage will be in the bottom direction which means again theta is equal to 90 only here also but the voltage will lack the lag the current by 90 degrees there voltage was leading right simple you can remember in inductance voltage was leading and the formula also v is equal to and in capacitance you have i is equal to you are not having voltage here right so that is why voltage is lagging like that okay that's your wish how you remember so this is i and we graph and the angle will be 90 degrees since voltage is down it is lagging the current by 90 degrees okay this is all about this video guys in the next video i'll explain about the voltage and current sources this is my first video in vw so if you are having any if if you are not able to understand at any point if you want me to make any changes let me know i'll definitely try to make it so thanks for watching the video till the end and if you're still having any doubts let me know in the comments section i'll be more than uh happy i'll be very very happy to clear all your doubts so thanks for watching the video till the end let's meet up the next coming video and also let me know whether you want me to continue this series or not [Music]