Transformer

TRANSFORMER It is an electrical device, which is used for changing the a.c voltage. Principle - A transformer is based an the principle of mutual induction i.e. whenever the amount of magnetic flux linked with a coil changes an e.m.f is induced in the neighboring coil. Working - As current in primary series changes, the magnetic flux linked with P1P2 and hence with secondary S1S2 changes. Due to self induction an e.m.f is induced in P1P2 and due to mutual induction an e.m.f is induced in S1S2

K is the constant called transformer ratio. A transformer, which increases the voltage, is called a step up transformer and a transformer, which decreases the voltage, is called step down transformer.

TRANSISTOR

A P-N-P junction transistor is obtained by growing a thin layer of n-type semiconductor or in between two relatively thick layer of p -type semiconductor.

Incase of P-N-P transistor majority carriers are holes. P-N-P is base on forward biase. It means the positive hole of emitter base battery V is connected to emitter and negative pole to base. Collector base junction is reverse biased. It means negative pole of collector base battery V is connected to the collector and its positive pole to the base. The resistance of emitter base junction is very low. So, voltage is quite small. The resistance of collector base junction is very high. So, voltage is quite large.