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Daily Archives: June 1, 2011


Why bicycle wheels are fitted with spokes?

Ajay asked:

“why bicycle wheels are fitted with spokes?”



  • To reduce overall mass
  • To provide greater Moment of intertia with the given mass
  • and some more factors

(Detailed Explanation To be posted soon)

By the time please referĀ http://en.wikipedia.org/wiki/Bicycle_wheel andĀ http://www.blurtit.com/q126941.html

Electric Potential

Lalit asks:

“Please explain electric potential in some other
words, other than every book,every author says..I
want something different..”


If you know the meaning of the word POTENTIAL, and already studied gravitational potential, then understanding Electric Potential would be quite easy.

We know the law of conservation of energy which states that “Energy can neither be created nor be destroyed; it can be transformed from one form to another or be transferred from one body to another”

If we imagine a positive point charge kept at a point, and if we want to bring another positive point charge closer to it, we have to perform some work. This work done is stored as the potential energy of the system. The work done in doing so depends on (i) the magnitude of the original charge and (ii) the distance at which the new charge is brought.

The Electric Potential at a point in an Electric Field is a measure of the work required to bring a unit positive charge taken from infinity to the point against the electrostatic force and brought without any acceleration.

Please refer to the following links for detailed information

Electric Potential and Potential Difference

Why hole is positive?

Mandeep asks:


“As we take a negative charge on the electron,when
electron leave there position,the left particle is
hole,my question is that why we consider hole as a
positive charge ,as a hole is a efficiency of
electron not containing any charge”


Answer: Hole is the deficiency (not efficiency) of an electron. It is assigned a positive charge for the sake of convenience of discussing it like a moving charge. When an electron leaves a site, the atom gets ionized and gets a positive charge. This is actually caused by the deficiency of electron. SO, we treat the vacancy of electron like a mobile positive charge. When an electron from the neighbouring atom leaves its ste and another electron fill a hole previously present, we treat it as if the hole has moved from one site to another.


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