MCQ Detailed View

Viscosity is a fundamental physical property of fluids that describes their resistance to flow. It is essentially a measure of internal friction within the liquid or gas. High viscosity means a fluid flows slowly (like honey), while low viscosity means a fluid flows easily (like water).

The unit of viscosity depends on the system of measurement:

1. 
   

   CGS (centimeter-gram-second) system:

   
   
   
   
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     The unit is Poise (P).

     
     
   
   
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     1 Poise = 1 dyne·second / cm².

     
     
   
   
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     In practice, viscosities are often expressed in centipoise (cP), where 1 P = 100 cP. For example, water at 20°C has a viscosity of approximately 1 cP.

     
     
   
   
   
   


2. 
   

   SI (International System of Units):

   
   
   
   
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     The unit is Pascal-second (Pa·s).

     
     
   
   
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     Conversion: 1 Pa·s = 10 P.

     
     
   
   
   
   

Now, examining the options given:

• 
  

  Decibel is a logarithmic unit used to measure sound intensity.

  
  


• 
  

  Torr is a unit of pressure (1 Torr = 1/760 of an atmosphere).

  
  


• 
  

  Poise is the correct unit of viscosity in the CGS system.

  
  


• 
  

  Hertz is a unit of frequency, meaning cycles per second.

  
  

Hence, the correct answer is Poise.