Saturday, 28 February 2015

How does a Photocopying Machine Works...??????

Photocopying machines are fairly complicated devices,but the basic principle is pretty simple.

At the heart of the process there is static electricity , a metal drum , a system of lenses and dark powder.

The machine's function depends on the fact that opposite electrical charges attract each other.

COPY A LETTER  :---  Let's follow the process of copying a letter :--

When you put the letter on the glass plate and push the start button, a metal drum below the glass is given a negative electrical charge.

A bright light shines on the original image and a system of lenses projects that image onto the drum.

Where the light strikes the surface of the metal drum the electrical charge disappears, but the dark parts of the image , that is the letters on the page, keep their charge.

THINK POSITIVE AND NEGATIVE  :--  At this point positively charged particles of black powder are deposited on the drum with its negatively charged letters.

Since opposite charges attract each other, the powder sticks to the plate where the letters are,but not to the rest of the drum, which has no charge.

Then a negatively charged piece of paper is pressed against the positively charged powder which is transferred to the paper.

Heat is momentarily applied to fuse the powder to the paper and out comes a warm copy of your letter.

So,its the interaction of positively and negatively charged parts in the photocopy machine  that allows the image to be copied from one piece of paper to other.


Sunday, 22 February 2015

Heat Transfer v/s Thermodynamics

Heat Transfer tells us :--

(1.) how ( with what modes ) heat is transferred
(2.) at what rate heat is transferred                     
(3.) temperature distribution inside the body      

Thermodynamics tells us :--

(1.) how much heat is transferred 
(2.) how much work is done         
(3.) final state of the system          ;)

Friday, 20 February 2015


I have some amazing google tricks guys. i m  definitely sure that you should also find these interesting ...

(1.)  GOOGLE GRAVITY  :--   Just type GOOGLE GRAVITY in your google search box but don't enter ... see the suggestions.
 from these suggestions click on i 'm feeling lucky  which appears on the right side of the  

''Google gravity'' suggestion..

  • google gravity
  • google gravity underwater
  • google gravity tricks

  • like this...

    after this u will find that every option on your screen will fall down  like :--  search box.., Google e.t.c.
    at this time you are able to search things by finding the search box..but the things you are going to search will also fall down.

    (2.)  BARREL ROLL  :--   Just type " do a barrel roll " in your search box and enter. 

    (3) ZERG RUSH : --.  Type    "ZERG RUSH " in your search box press enter and wait for few seconds .

    (4.)  GOOGLE SPHERE  :-- Type GOOGLE SPHERE in your search box and do the same process as you have done in GOOGLE GRAVITY...

    i hope you will enjoy guys... :)

    Wednesday, 18 February 2015

    PROXIMITY SENSOR....$$$$$$$

    A Proximity Sensor is sensor able to detect the presence of nearby objects without any physical contact.
    A Proximity sensor often emits electromagnetic radiation , and looks for changes in the field or return signal.

    Operating Principle of Proximity Sensor :-

    A high frequency magnetic field is generated by coil in the oscillation circuit. 

    When a target approaches the magnetic field , an induction current flows in the target due to electromagnetic induction.

    As the target approaches the sensor , the induction current flow increases , which causes the load on the oscillation circuit to increase.

    Then oscillation attenuates or stops. 

    The sensor detects this change in oscillation status with the amplitude detecting circuit , and outputs a detection signal.