MCQ Detailed View

A photostat machine, commonly known as a photocopier, is widely used to make copies of documents quickly and efficiently. The machine works on the principle of electrostatic image making, which is a combination of photography and electrostatics.

The process begins when light from the original document shines onto a photoconductive drum. The areas of the drum exposed to light become conductive and lose their static charge, while the dark areas retain the charge. This creates an electrostatic image on the drum corresponding to the original document.

Next, toner powder, which is electrically charged, is attracted to the areas of the drum that still carry the static charge. This step makes the image visible in powder form. The toner is then transferred onto a sheet of paper, and heat or pressure is applied to fuse the powder onto the paper, producing a permanent copy of the document.

Key points about electrostatic image making:

1. 
   

   Photoconductivity: The drum conducts electricity only when exposed to light.

   
   


2. 
   

   Electrostatic attraction: Toner particles stick to charged areas of the drum.

   
   


3. 
   

   Toner transfer and fixing: Heat or pressure bonds the toner to paper to create a clear copy.

   
   

Other options are incorrect:

• 
  

  Electromagnetic image making (Option 1) is unrelated to photocopying.

  
  


• 
  

  Magnetic image making (Option 2) is used in magnetic storage devices.

  
  


• 
  

  Thermal image making (Option 3) is used in thermal printers.

  
  

The use of electrostatics allows photostat machines to produce accurate, high-speed copies and has made them essential in offices, schools, and printing businesses. Understanding this principle helps students link physics concepts like static electricity and photoconductivity to real-world applications.

In conclusion, a photostat machine works on electrostatic image making (Option 4), combining light, charge, and toner transfer to reproduce documents efficiently.