What is Resistance ?

Resistance is a kind of obstruction offered to the path of Current. And Current is the nothing but the flow of electrons. 

Electrons flowing through a conducting wire

Therefore it is the movement of electrons that matters, which means if a body has abundance of free electrons, we call it a good Conductor and if a body has no free electrons, we call it Insulators .

Insulators has very high value of resistance.

Conductors has negligible resistance.

There are some more parameters on which resistance varies, they are :

• Cross-section Area of the conductor
• Length of the conductor

Resistance is indirectly proportional to the Cross sectional Area of the conductor i.e. more the Area of the conductor is, lesser will be the resistance offered to the flow of electrons.

Resistance is directly proportional to the length of the conductor i.e. more the length of the conductor, more will be the resistance offered to the flow of the electrons, which means electrons have to travel longer distance, and with increase in distance obstructions increases as well.

NOTE: if you test resistances of same material of conducting wires varying only in the cross-sectional-area with a DIGITAL MUTIMETER, you will find that the wire with larger area offers less resistance, and the value on the multimeter will be lesser.

Similarly, you can also test two conducting wires of same material but of varying length this time, you will find that the resistance offered by the longer wire is far more than that of shorter one.

As every quantity we use in our daily life has got units, Resistance has units of Ohm i.e. it is measured in Ohms.

Omega(Ω) is its symbol.

1KΩ = 1000 Ω

1MΩ = 1,000,000 Ω

Its unit Ohm is named after its discoverer, whose name is Georg Simon Ohm, He was born in Bavaria(now in Germany) in 1787.

See Bavaria in Map of Germany

Ohm was able to demonstrate in 1827 that the electrical resistance of a conductor such as copper varied in proportion with its area of cross-section, and the current flowing through it is proportional to the voltage applied to

it, as long as temperature is held constant. Fourteen years later, the Royal Society in London finally recognized

the significance of his contribution and awarded him the Copley Medal.

Today, his discovery is known as Ohm’s Law.

Gerog Simon Ohm

What is a Capacitor ?

Capacitor is an electronic component, which is used to store electric charge, therefore it can also be viewed as a battery but not that strong one, although physical construction of battery is completely different from that of capacitor.

Capacitor is made up of two conducting plates separated by an insulating material called dielectric. 

                                   

 Types of Capacitors

Capacitors comes in many varieties according to different usages, they are :

• Electrolytic Capacitor
• Tantalum Capacitor
• Polyester Film Capacitor
• Polyester Film (Box Shaped) Capacitor
• Ceramic Capacitor

Funny Thing about Discovery of Capacitance

CAPACITANCE WAS DISCOVERED BY CHANCE

A Bishop of  POMERANIA ( it is a historical region on the south shore of Baltic Sea) named Ewald Georg von Kleist was doing an experiment at the close of 1745 in October.

See Pomerania on map( Its in Europe)

Von Kleist wanted to isolate the electricity. He wanted to actually trap electricity in a jar containing water and to see how it looked like when trapped inside water.

He actually put a wire connected to a high voltage electrostatic generator into a jar containing water, and hold that jar in his hand. He thought, he would be able to trap electric current coming from high voltage electrostatic generator via conducting wire into water, but nothing happened like that. Then he disconnected the conducting wire from the electrostatic generator, and when he touched that conducting wire dipped in water with his naked hand, he experienced a painful electric-shock. He was very confused with this, that how an unconnected wire gave him electric-shock. He was unaware of the fact that it was because the unconnected wire stored some of the electric charge in it when it was connected to electrostatic generator. This concept of storage of electric charge by conductors later on formed the basis for making capacitors.

Later on the Dutch physicist Pieter van Musschenbroek invented a similar capacitor which he named Leyden jar, after the name of Leyden University, where he worked.

It is very astonishing for me to realize that when people in our country were ruled by the Mughal Dynasty and Britishers were about to come to rule India, there were also people in other parts of world who were busy in discovering and inventing things.

Fun with Electronics

Today I really had good time, when I started examining my P.S.U.(Power Supply Unit) of my PC. Few days back, the P.S.U. blew off due to fluctuation in the voltage. I didn't connect my PC via any U.P.S.(Uninterrupted Power Supply) which could be the possible reason of why my P.S.U. blew off.

I went to a mechanic, he asked me to submit the P.S.U. and the repair would cost around  Rs 400. Actually there were two thoughts coming in my mind

1.  Why shouldn't I do it by myself, after all, that mechanic was hardly a graduate, where on the other side, I am a "Computer Engineer".
2. I am a skinflint .

The first thing I did, as all use to do, was watching YOU_TUBE VIDEOS . I got to know that a fuse could have blown and that can be replaced with not much difficulty. I was mesmerized and felt very happy that I have saved Rs 400, because the solution to this problem seemed so easy. I started kind of making inventory of things which I would be requiring for my little Sci-Fi Expedition. I went to one and only shop of our town to buy 1) a fuse 2) Soldering iron 3) Solder wire

The shopkeeper proved to be another THUG , he charged me a fuse of just few paise to Rs 10 and Soldering iron of just Rs 30 to Rs 60 and Solder wire of Rs 2 to Rs 10. Being helpless, because there was not any other such shop in our small town, I purchased all those tools for my Sci-Fi Expedition .

I came home and started my exploration, I extracted my P.S.U. from the PC cabinet and started removing its bad fuse. I fixed it with brand new fuse which I bought from that THUG. The feeling was like I landed on the moon or was just about to initiate a Rocket Launch , Wow, I can't explain it how I felt at that moment.
Now the only thing left was to check by plugging it again and see whether my little expedition succeeded or not. I plugged the wire into the socket, everything was fine, the fuse was tight and good, I was very happy and confident and full of excitement to see my P.S.U. work again.
So, the moment came when I was about to press THE MIGHTY SWITCH,

I pressed it and my face was like

Mission Failed !!