Tuesday, October 20, 2015

Faraday's law of electro magnetic induction

Faraday discovered that when he moved a magnet near a wire , a voltage is generated across it . When the magnet was held stationary , that is if we don't move the magnet then no voltage is generated .

This means voltage exists only when the magnet was moving . We call this voltage as " INDUCED EMF ( E ) " .

This also means voltage existed because of magnetic field . This field has both horizontal and vertical components. But only vertical component contributes to the generation of electricity .

Let theta be the angle between the normal and vertical component of magnetic field .

Then ,

Faraday's law can be written as ,

Induced voltage E is proportional to the rate of change of magnetic flux ' theta ' .

through the area of loop of conductor .

voltage is denoted with the negative sign to indicate that the voltage opposes the rate of change of magnetic flux .

Sunday, October 11, 2015

Hanuman challenged Arjun .....

Hanuman was present in the times of Ramayan . How can he be present in Mahabharat time? The answer to this question is Hanuman is immortal .

Means , there is no death for Hanuman.

Once Arjun went to Rameshwaram , to visit the place where Ram had worshipped God Shiv before leaving for Lanka.

That time , he visited the famous bridge to Lanka from Rameshwaram through sea. Now it is in ruins. Since the bridge was made of large stones , stones were dislocated.

By seeing this, the great archer himself , Arjun pitied about condition of Ram who had taken the help of monkeys to construct the bridge.

Arjun said " Instead of asking monkeys for help , Ram could have construct the bridge with arrows . Then it would have been permanent ". 

A monkey who was staying on nearby tree , heard Arjun's words.

It came infront of him and challenged Arjun to construct a bridge using arrows . Arjun accepted the challenge.

Soon bridge of arrows was  ready !

Monkey said it will check the durability of bridge by itself .

Monkey started to walk on bridge. But wherever it was keeping its foot , there was a big pot . Soon bridge started to collapse !

This made Arjun to think about foolishness of his challenge .

Monkey was not an ordinary monkey , it was Hanuman himself !

Thursday, October 1, 2015

What is Tyndall Effect and example in our life ?

We all have seen ribbons of light peeking through window in the morning .This is just an example of Tyndall Effect.

What is Tyndall Effect?

This effect refers to scattering of light when it passes through a colloid system composed of smaller particles. One more example for this is ----

We have 2 jars of water . One jar contains pure water and other one contains water with impurities or particles. Now we will pass a beam of light through both of them..

The light passing through jar containing pure water emerges as it is , without any change . But when the light passes through the jar containing water with impurities , then light will undergo either reflection or refraction or both.

This effect is widely used in Chemistry labs .