electronic
transister we have dealt with two eiement devices in semiconductor materials and now we will look into three element device known as a transister is formed by tha use of two PN junction one junction is biased in tha forward direction and tha other junction in tha reveres direction we can arrange this three element device in two ways i.e PNP NPN there is one major difference between tha two types in that tha npn has a better frequency gain per response than tha pnp