Saturated Core Reactor acts as a variable inductance connected in series with load across an A.C power supply.

It is a device which converts the light energy into electrical energy. When light is allowed to fall on this cell, the cell generates a voltage across its terminals.

The speed of  DC motor  can be control by using  SCR  in AC circuit  as shown in the below figure.

PLC stands for programmable logic control. It is computer designed to be used in industry. It controls the different process and is programmed

The bipolar power transistor is a three layer NPN or PNP device within the working range, the collector current IC is a function of the base current IB

These type of transducers requires an external power supply and therefore output is equal to the variation in a physical parameter such as pressure, temp etc.

The PUT stand for Programmable Unijunction Transistor, it is actually a type of Thyristors and not like the UJT at all.

The phototransistor has a light sensitive collector base PN junction. It is exposed to incident light through a lens opening in the transistor package.

The diagram of magnetic amp or magnetic amplifier is shown in figure below, only silicon diodes are added in series with each winding of the saturated reactor.

LVDT is a positive or magnetic displacement transducer; it is commonly used to measure force, weight, pressure and acceleration