Thursday, 8 September 2011

Lenses

Classified into:

Converging and Diverging lens.



The diagrams above show the parts and the movement of the rays as they pass through the converging lens.

Definition of the parts:

1.Optical center C: The midway between the lens surfaces on its principal axis. Rays passing through the optical center will not be refracted.


2.Principal axis: The horizontal line passing through symmetrically through the optical centre of the lens. 


3.Focal point F (principal focus): The point at which all rays parallel to the principal axis converge to after refraction by the lens. 


4.Focal length f: The distance between optical centre C and focal point F.


5.Focal plane: The plane which passes through F and P (perpendicular to principal axis)









This table shows the movement of the rays as compared to its focal length.


*Diagrams taken from textbook.

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