Refraction of light through a Convex Lens
Lens diagram a cross section through the centre plane.
Simple convex (curves outwards) lens
Simple concave (curves inwards) lens
Convex lens Concave lens
Lens is in a vertical plane, straight up and down on the page.
Lens Air
Light ray
Light ray is horizontal (at a right angle) to vertical lens
Extension of right ray Light ray is horizontal (at a right angle) to vertical lens
Extension of right ray Light ray is horizontal (at a right angle) to vertical lens
Centre line of the lens Extension of right ray Light ray is horizontal (at a right angle) to vertical lens
Extension of right ray Light ray is horizontal (at a right angle) to vertical lens Centre line of the lens
Right angle to the centre line of the lens Extension of right ray Light ray is horizontal (at a right angle) to vertical lens Centre line of the lens
The perpendicular
Right angle to the surface of the lens
Centre line of the lens
Perpendicular to the centre line of the lens, passing through the centre point of the lens Centre line of the lens
Light ray
The focus or focal point
F Focus
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F Focal length Focus
This distance from the centre of the lens to the focus point, will be given to you as a point on a diagram or a measurement such as 3cm. F Focal length Focus
F Focal length Focus
F Focal length Focus
2 x focal length F Focal length Focus
2 x focal length F Focal length Focus
2 x focal length FF2F2 Focal length Focus
2 x focal length F1F1 F2F2 Focal length Focus
Focal length 2 x focal length F1F1 F2F2 Focus
Focal length 2 x focal length F1F1 F2F2 Focal length Focus
Focal length 2 x focal length F1F1 F2F2 Focal length Focus
Focal length 2 x focal length F1F1 F2F2 Focal length Focus
Focal length 2 x focal length F1F1 F2F2 F1F1 Focal length Focus
Focal length 2 x focal length F1F1 F2F2 F1F1 Focal length Focus
Focal length 2 x focal length F1F1 F2F2 F1F1 Focal length 2 x focal length Focus
Focal length 2 x focal length F1F1 F2F2 F1F1 Focal length 2 x focal length Focus
Focal length 2 x focal length F1F1 F2F2 F1F1 F2F2 Focal length 2 x focal length Focus
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2 Object located beyond 2 focal lengths (F 2 )
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2 Light rays converge at this point.
F1F1 F1F1 F2F2 F2F2 A real image is formed. A real image can be projected onto a screen.
F1F1 F1F1 F2F2 F2F2 The image is inverted (up-side down) and smaller than the original object.
F1F1 F1F1 F2F2 F2F2 When the object is located beyond 2 focal lengths (F 2 )
F1F1 F1F1 F2F2 F2F2 The image created is real, inverted and smaller than the original object.
F1F1 F1F1 F2F2 F2F2 When the object is located beyond 2 focal lengths (F 2 ) The image created is real, inverted and smaller than the original object. The rays converge between 1 and 2 focal lengths
F1F1 F1F1 F2F2 F2F2 Other rays can be added from different points on the object
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2 These extra rays all converge at the same point between 1 and 2 focal lengths.
F1F1 F1F1 F2F2 F2F2 These extra rays are unnecessary for our purposes.
F1F1 F1F1 F2F2 F2F2 Draw rays only from the top point of your object. This will keep your diagram simple and easy to understand
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2
F1F1 F1F1 F2F2 F2F2