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 In a compound microscope the focal length of objective lens is 1.2 cm and focal length of eye piece is 3.0 cm. When object is kept at 1.25 cm in front of objective, final image is formed at infinity.  Magnifying power of the compound microscope should be :

  • Option 1)

    200

  • Option 2)

    100

  • Option 3)

    400

  • Option 4)

    150

 

Answers (1)

best_answer

As we have learned

Compound Microscope -

m= -\frac{v_{o}}{u_{o}}\cdot \frac{D}{u_{e}}
 

- wherein

v_{o}\, and \, u_{o} is distance from objective.

u_{e} Distance from eyepiece.

Maximum magnification m= -\frac{v_{o}}{u_{0}}\left ( 1+\frac{D}{f_{e}} \right )

 

 f_e = 3cm \\ f_0 = 1.2 cm \\ u_0 = 1.25 cm , v_e = \infty \\ \Rightarrow \frac{1}{V_0 }= \frac{1}{f_0}+ \frac{1}{u_0}= \frac{1}{1.2}-\frac{1}{1.25}

 

Magnification = \frac{v_0}{u_0}\cdot \frac{D}{f_e}= \frac{30}{1.25}\times \frac{25}{3}= 200 

 

 

 

 


Option 1)

200

Option 2)

100

Option 3)

400

Option 4)

150

Posted by

Avinash

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