PHYSICAL INTERPRETATION OF RLC

Hello folks,

A simple question based on which, people can differentiate an Electrical Engineer from a Non-Electrical person is a quiet logical question. To answer this question one need to have the basic knowledge regarding RLC components without whom Electrical Engineering is incomplete. This is also a famous interview question.

And the question is: WHAT IS PHYSICAL INTERPRETATION OF RLC?                                      

[i.e. How can you explain the basic elements of Electrical Engineering (R,L,C) to a non-electrical guy?]

There are numerous ways to answer this question as per your imagination and understand of RLC. But here I would like to share one co-relation relating to our daily life. Everyone is free to define their own analogy for RLC components.     

Resistor, Capacitor and Inductor are the most primary components in Electrical technology.

Resistors are the components the dissipate energy (usually in the form of heat) and this energy cannot be recovered as it has no memory. As the symbol shows, the resistor can be related to speed breakers on the road because of which the speed of a vehicle is reduced. The zigzag shape of symbol of resistor indicates the same.

Capacitor is an element that can store potential energy, while energy is transferred from load to source, in the Potential form. It can store voltage as the memory and hence, voltage across capacitor is a state variable. To understand how it stores energy, let us consider a simple analogy of real world – Water Purifiers in our home. It has tap at the bottom and a pipe at top to fill the purifier. Let us assume that water is flowing continuously through the pipe into the purifier and tap at bottom is also open to facilitate continuous outflow of water. The inflow and outflow of the water can be so adjusted that there is some specified level of water built up and this is the buffer water. So the water that is getting stored in the purifier is like stored potential energy. This is how we can relate capacitor to water purifier. The input flow of water is somewhat like input flow of charges in the capacitor. This is called charging of capacitor. The flow of water outside purifier is the flow of charges outside capacitor and this is discharging of energy in capacitor (discharge of water outside purifier). The capacity of water tank is analogous to the capacitance value of the capacitor. The height of the water that is being stored in the water tank is the potential of the energy and it is the voltage potential of the capacitor. So the capacitor can be undoubtedly perfectly related to water purifier.

Inductor is an element that can store kinetic energy and here flow of current through inductor is a state variable. To understand inductor let us consider a flowing mass of water and the rotating turbine in specific direction. So here the rotation of the blades of turbine is by virtue of the fact that energy is stored in the flowing water body and wheel rotates when the water is flown onto it. So the flowing water mass has the kinetic energy stored in it by the virtue of it being in motion. It is that energy which inductor stores equivalently in case of electric circuits and the water flowing is the current. So the energy stored by the virtue of current flowing is the kinetic energy which is stored in the inductor.

Thank you for your time and feel free to share topics of your area of interest.