this radio I am going to show you how to test a transistor and led with the help of multimeter so let's start the lesson do you know what is it it is a transistor transistor is an electronic device which is used for amplification and switching there are two types of transistor NPN transistor and PNP transistor transistor have a three terminal collector emitter and base this is the symbol of NPN transistor here and p-type semiconductor p-type semiconductor is sandwiched between n-type semiconductor NPN transistor have three terminal collector base and emitter arrow sign is towards emptor similarly PNP transistor have also three terminal collector base and emitter but arrow sign is towards base PN P type semiconductor is defined as n-type semiconductor is sandwiched between p-type semiconductor this is the front view of the transistor front view of the transistor is of flat type it's a plane this is the back view of the transistor it's off dome shape and there is a there is a a little circle on the backside of the transistor to know the term of the transistor first of all you have to put you have to put flat face in front of your face and then the rightmost or terminal of the transistor is emitter and the middle terminal the transistor is base and the last one that is leftmost terminal of the transistor is collector to test it transistor with the help of multimeter first of all you have to put this rain switch to HFE mode and then you have to connect a transistor in if the transistor is of NPN type then you have to put the transistor in NPN side and if your tongue sister is of PNP tied then you have to put your transistor in PNP side as I had put the rain switch to HIV mode here H stand for H parameter F stands for current gain and e stands for common emitter configuration as I said my switch line to hf e mode now i have to connect my transistor to this section as my transistor is of NPN type so I am going to connect my transistor to NPN section an NPN section have emitter whole base whole and collector whole I have to connect the respective emitter base and collector end of the transistor to the respective emitter base and collector whole of the multimeter as I connected emitter terminal of the transistor to the emitter whole and the base terminal of the transistor to the base whole and the collector terminal the transistor to the collector whole now we got a value of H Fe that is 343 so in this way we can easily calculate or easily test the transistor with the help of multimeter HFE value of every transistor is fixed the range of HIV value is from ten to five hundred every transistor have their unique HFE value HFE value is a multiplying factor amount of current applied to the base terminal of the transistor suppose we apply 1 milli ampere of current to the base thermal of the transistor which is connected to the common emitter configuration then the amount of current that we get from the collector side of the transistor is multiplied by 342 that is hf field value of the transistor so there is amplification of 1 milli ampair of the current to 342 milli ampair of the current that we have get from the collector of the transistor so with the help of HIV value of the transistor we can know the multiplying factor or amplifying factor of the transistor very easily with the help of multimeter now we are going to test a led with the help of multimeter Aladin stands for light emitting diode this is diode when it is connected to the forward vise it will emit light so it is called light emitting diode it has to tunnel P terminal and Anton the longest terminal of the diode is P Turner and this little solder terminal of the diode is Anton as you see here that the the P terminal the diode have an arrow have a very narrow strip here but the n-terminal the diode have a very wide strip here so by seeing the diet you can easily know which one is P terminal and which one is anton or the diode to test a diode with the multimeter we have to put the rain switch to the connectivity or the diode mode as I had put my rain switch to the connectivity or the diode mode I have to put the red probe to the voltage o milliampere jack and the black probe to the common Jack now I am going to connect a red probe of multimeter to the P tunnel of the diode and the black probe of the multimeter to the N terminal of the third as I connected it it closed it means the diode is in forward wall vice and is it is in working state but if I connected a black probe to the internal of the diode sorry Peter Lorre the diode and the red probe to the internal diode the light will not flow it means that diode is not working in the reverse bias so diode is working in only forward bias that is when we connect a positive terminal of the battery to the peeterman of the diode and the negative terminal of the battery to the N term of the diode and this is called forward bias connection and the diode will in working state as you see that the light is LED is glowing so it is working so thank you for watching my videos like my videos share my videos and comment down below