Optical Instruments

7.2 Optical Instruments
 
Application of lenses in optical instruments
 

 
Formation of the final image by a microscope
 
 

 
  Object is between F and 2F
Image position Image is further than 2F
Image characteristics
  • Real 
  • Inverted 
  • Magnified
 
  Object is between F and the optical centre
Image position Image is further than F
Image characteristics
  • Virtual
  • Upright
  • Magnified
 
Magnifying Power of Microscope 
Magnifying power of objective lens X Magnifying power of eyepiece
 

 

Formation of the final image by a telescope
 

 

 
  Objective at infinity
Image position Image at F
Image characteristics
  • Real
  • Inverted 
  • Diminished
 
  Object at F
Image position Image at infinity
Image characteristics
  • Virtual
  • Upright
  • Magnified
 
The distance between the objective lens and eyepiece

\( f_o + f_e\)

  where \(f_o\) = focal length of objective lens,

                  \(f_e\) = focal length of eyepiece

Optical Instruments

7.2 Optical Instruments
 
Application of lenses in optical instruments
 

 
Formation of the final image by a microscope
 
 

 
  Object is between F and 2F
Image position Image is further than 2F
Image characteristics
  • Real 
  • Inverted 
  • Magnified
 
  Object is between F and the optical centre
Image position Image is further than F
Image characteristics
  • Virtual
  • Upright
  • Magnified
 
Magnifying Power of Microscope 
Magnifying power of objective lens X Magnifying power of eyepiece
 

 

Formation of the final image by a telescope
 

 

 
  Objective at infinity
Image position Image at F
Image characteristics
  • Real
  • Inverted 
  • Diminished
 
  Object at F
Image position Image at infinity
Image characteristics
  • Virtual
  • Upright
  • Magnified
 
The distance between the objective lens and eyepiece

\( f_o + f_e\)

  where \(f_o\) = focal length of objective lens,

                  \(f_e\) = focal length of eyepiece