The most common components in an electric circuit are Resistors, Capacitors, LEDs, Transistors, Inductors and Integrated Circuits.
Resistors
A resistor is used to control voltages and currents in a circuit. Depending on what you want to do, the resistors you use will vary. If you use a 9V battery and you want to turn on an LED, when you connect the LED directly to the battery too much current will flow through the LED and cause it to blow. A resistor prevents this from happening.
Capacitor
A capacitor can be charged like a battery and is often used to cause a time-delay in a circuit. It’s commonly used for removing noise and making the supple voltage of a circuit more stable. There are different types of capacitors, they most commonly divided into polarized and non-polarized.
LED
LED- light emitting diode- are used to give visual feedback from our circuits. You can tell if your circuit has power if your LED glows. You can find LED’s everywhere they are in laptops, phones, cameras and in our cars.
Transistors
A transistor is a switch controlled by an electric signal. When you put about 0.7 volts between the base and the emitter, you can turn it on. However, instead of just having two states (ON, OFF) like a regular switch, it has ‘a bit on’ by controlling the current that goes through it’s base.
Inductor
An inductor is basically just a coil of wire and you can even make your ones by looping some wire. Inductors are often found in filters, sensors, motors and as energy storage.
Science Blog 