What Is an Amplifier?SECTION 15199WATER IS ALWAYS A GREAT ANALOGY. A smallamount of power on the handle allows a very largeamount of power to flow from the source throughthe amplifier.Lesson 49Transistors as Amplifiers and Defining CurrentSo, what is an amplifier? It takes a small signal andmakes it bigger. Signals are made of both voltageand current. The definition from dictionary.com is verysimple.ReviewWe’ve applied the transistors as amplifiers in a fewways. You may not have recognized it at the time.Let’s review what you did.Remember the Night LightIts action is shown in Figure L49-1. The signalgiven to the base of the NPN transistor isamplified.The voltage divider created by the potentiometerand the LDR control the voltage to the base of thetransistor. Remember, the voltage at that point isdependent on the following:1.The setting of the potentiometer2.The amount of light on the LDRam·pli·fy—verb. 1. To make larger or morepowerful; increase. 2. To add to, as byillustrations; make complete. 3. To exaggerate.4. Electronics—To produce amplification of or toamplify an electrical signal.am·pli·fi·er—noun. 1. One that amplifies,enlarges, or extends. 2. Electronics—A device,especially one using transistors or electrontubes, that produces amplification of anelectrical signal.