INTRO TO ELECK-TRONICS (ELECTRONICS)

 INTRODUCTION TO ELECTRONICS - A TECHNOLOGY  GIG

                                                         posted on : 17-03-2022                               Author : K.Nithiya

Hai Everyone !!! This Blog session takes you deep for Introduction into  Electronics.

      Electronics is one of the first components that we're going to talk about is resistors because typically, you'll find them in almost every electronic circuit resistors are designed to limit the amount of current flow in in the circuit and you could calculate the amount of current flowing in a circuit using ohm's law v equals ' ir' v stands for voltage measured in volts i represents the current measured in amps r is the resistance measured in ohms.The current flowing through a resistor is the voltage across the resistor divided by the resistance itself so let's say we have a battery attached to a resistor the long side is the positive terminal of the battery the short side is the negative terminal of the battery.

 

 PRACTICAL APPROACH 

Let's use a 12v battery conventional current is going to flow from the positive terminal of the battery through the resistor back to the negative terminal of the battery. Conventional current flows from a high potential to a low potential but in actuality electrons flow in the other direction from the negative terminal to the positive terminal so that's really what's happening in the circuit electrons are the charged currents they're the ones that are moving through the metallic conductor ,but now let's make a table that shows the relationship between resistance and current so let's say the resistance is 3 ohms using this.

 FORMULA

 If we take 12 volts divided by 3 ohms we're going to get a current of 4 amps now what if we increase the resistance let's say from 3 ohms to 6 ohms what's going to be the current well using the same formula , if we divide 12 volts by 6 ohms we're going to get 2 amps and so note what note the relation between resistance and current if we increase the resistance in a circuit the current decreases and so we could use this device to control the amount of current that is flowing in a circuit, if you want to increase the current you can decrease the resistance if you wish to decrease the current increase the resistance now sometimes you may need to decide what resistor to use in a circuit and one important consideration that you need to take into account is the power rating of a resistor, so let's say we have a battery attached to resistor and let's say this is a 100 ohm resistor and the power rating is one half watts power is equal to voltage times current. It's also equal to the square of the current times the resistance and it's equal to v squared over so you could use any one of those three formulas to calculate power now this is important because if you apply too much power to a resistor or too much voltage the resistor can burn up it can get hot and that could create a lot of problems so you need to control how much power you deliver to a resistor because it can only dissipate so much without damaging itself and other nearby components so what we're going to do in this example is given the resistance and the power rating of the resistor.Then what is the maximum voltage that we should apply across this resistor so we're going to use this formula p is equal to v squared over now , because we're solving for v we're going to rearrange the equation 

 METHODOLOGY

I'm going to multiply both sides by 'r' so i get squared is equal to the power times the resistor taking the square root of both sides. we get the formula to calculate the maximum voltage that should be applied across the resistor so v is equal to the square root of 'p' times. R so here we have a one half watt resistor and the resistance is 100 ohms so half of a hundred is 49 and the square root , it mean it's 50 well half of a hundred is not 49 it's 50.but you know what it is easy to take the square root of 49 that's 7. so if you want to get a ballpark of your answer you know it's close to 7. The square root of 50 is about 7.07 volts.so that is the maximum voltage that should be applied across this resistor if you don't want it to overheat now the next thing that we need to talk about is how you can connect multiple resistors together if you wish to increase the resistance in a circuit you want to add resistors in series because the total resistance of resistors connected in series is the sum of each individual resistor so the more resistors that you add the greater the total resistance will be in a parallel circuit the more resistors.You add in parallel to each other the total resistance actually goes down to calculate the total resistance you can use this formula it's one over r one plus one over 'r' two plus one over r three raised to the minus one and I'm going to give you an example of that shortly but right now i want you to understand something in a series circuit there's only one path for the current to flow and this is the only path that it can flow from a to b in a parallel circuit there's multiple paths for the current to flow going from a to b the current can flow through r1 it can flow through r2 and it can flow through r3 and so that could help you to distinguish whether if two components are connected in series or in parallel.If there's only one path for the current to flow it's connected in series , if there are multiple paths for the current to flow it's connected in parallel now there's some other important things to take into account here because in a series circuit the current flowing through each resistor is the same so the current flowing through r1 is called i1 the current flowing through r2 is i2 each of these currents they're the same current i1 is equal to i2 and that's equal to i3 now in a parallel circuit the voltage across each resistor is the same.so the voltage across r1 is v1 the voltage across r2 is v2 because they're connected across the same two points so that's another thing you need to be aware of when dealing with series circuits and parallel circuits in a series circuit the current flowing through each resistor is the same in the parallel circuit the voltage across each resistor is the same now let's say we have two 10 ohm resistors there's a lot of things we can do with that with those two 10 ohm resistors we can get three different resistor values we could use one of the two resistors to get a resistance value of 10 ohms or if we wish to increase the resistance.we can connect the two resistors in series and so the total resistance across these two points.Let's call it point a and b is now r1 plus r2 so we get 20.

EPILOGUE

 Now if we wish to decrease the resistance.we can connect the two resistors in parallel now whenever you connect two resistors in parallel.if the two resistors have the same value if they're identical the total resistance of the two identical resistors will be half of their respective value. so it's going to be 5 ohms so thus,if you want to increase the resistance connect resistors in series.

so