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• # Understanding Electrical Resistance

Dear friends, today the topic of my lecture is - Understanding Electrical Resistance.

In this lecture we will try to understand what is meant by the resistance when electricity passes through a material.

To start with we already know that materials can be broadly put under two categories - conductor and insulator, depending upon whether they allow the electric current to pass through them or not.

So whenever we try to pass electric current through a material it will try to impede it's flow and this property is known as electrical resistance. Accordingly the current (more or less) will flow through it depending upon this resistance

Electrical resistance is the basic property which is utilized in designing of electrical circuits ranging from basic electrical wiring in our houses to wiring in complicated computerised electro-mechanical super machines.

Metals like copper, aluminium, iron etc are good conductors of electricity and their electrical resistance is less - copper being the minimum. This property of copper is used in the electric wiring in our houses where copper wires are often used. When electricity flows through these wires you can not touch them as you will get the shock and to protect us from the shock these wires are covered with some non conducting material (insulators) like rubber or plastic etc.

Let us understand the electrical resistance more clearly by taking an example of a metal wire. It will have some electrical resistance. It is seen by experiments that if we increase the length of this wire the resistance increases proportionally. On the other hand if we increase the diameter (thickness) of this wire the resistance decreases in inverse proportion. So these are the properties used in designing the resistances for a particular purpose.

The famous Ohm's law in physics states that if a voltage V (unit-Volts) is applied across a conductor having a resistance of R (unit-Ohm) and due to this a current I (unit-Ampere) flows through it then -
V = I x R
This is the basic mathematical relation of resistance with the applied voltage and current flowing through it.

When a sufficient electric current flows through a metal wire which has bigger resistance (like the one we have in our electric heater), the wire starts heating up and this property is used in electrical heaters, geysers etc.

I hope that I have made the concept of electrical resistance clear to you. Thank you.
• Nicely explained about the electrical resistance. The measurement of electrical resistance can be made by using the ohm meter. Higher the resistance lower the conductivity. Lower the resistance, higher the conductivity.
A useful subject especially for the beginners who are just starting the study of electricity chapter in physics. Appreciations to the author for his well-explained lecture.

drrao
always confident

• Nicely explained about resistance. Unit is resistance is Ohm. Its basic quality of a substance to oppose flow of elecriticity in it. Aluminium, silver and copper are said to be the best conductor of electricity thats the reason these metals are used in winding of electric motors used in electric appliances.
Sanjeev

" It is better to be hated for what you are than to be loved for what you are not" ... Andre Gide

• Although the author has added with some technical matter which for a non-technical person like me would be difficult to understand but to my experience the introduction is impressive with whole lot of information kept inside in order to keep the interest of the readers till the end. Good one.

• Took me back to my school days. The lesson was nice and smooth.
The stronger a light shines the darker are the shadows around it.

• Indeed, a good lesson taught by you and learned by others. You have explained it in a detailed manner that it could be understood easily as to what is "Electrical Resistance". You have the ability to explain methodically.
No life without Sun

• It is clearly understood. Electrical resistance in conductors and insulators are well described with the example of the insulated material used to cover the metal wire. It is one of the basic lessons of electricity and the Ohm's law is well presented here.
Sankalan

"Life is easier when you enjoy what you do"

• A nice lecture. Well explained. We read about these things in our high school times.

There is clarity in explaining the things. Overall a good lecture.

Thoughts exchanged is knowledge gained.

• Mr. Umesh: You have beautifully explained Ohm's Law and the concept of resistance. In fact, I have just now asked a little girl of VIIth standard to read this lecture (given by you) and she has stated that she has understood the basic concept (of resistance) very clearly.
Beware! I question everything and everybody.

• Resistance is a force which tend to oppose the flow of current. If you increase the resistance, the flow of current would be dropped. I think we all familiar with the mostly used equation V=IR. It tells the whole story of relationship between resistance, voltage, and current. Thanks!