13.1 Lenses
Predicting Images in a Convex Lens
The Principal rays A ray parallel to the principal axis is refracted through the principal focus (F ).
The Principal rays A ray through the optical centre (O) continues straight through without being refracted.
Ray diagram when the OBJECT is beyond 2F S- Smaller A- Inverted L- between F and 2F T- real
Ray diagram when the OBJECT is AT 2F S- same size A- inverted L- on 2F T- real
Ray diagram when thE OBJECT is BETWEEN 2F and F S- larger A- Inverted L- beyond 2F T- real
Ray diagram when the image is AT F No Image
Ray diagram when the image is between F and O S- larger A- upright L- between 2F’ and F’ T- virtual
animation.com/optics_interactive/converging_lens_con vex_positive.htm
Predicting Images in a Concave Lens
Any incident ray parallel to the principal axis will refract as if it had passed through the principal Focus. Concave Lens Characteristic Rays
Any incident ray passing through the Optical Centre will pass unrefracted (straight through).
Concave Lenses All Cases S- smaller A- upright L- in front of F T- virtual
Homework Pg. 561 #2, 3, 5, 6, 8