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.
Light ray is horizontal (at a right angle) to vertical lens
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
The perpendicular
The perpendicular
Right angle to the surface of
the lens
Centre line of the lens
Centre line 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
The focus or focal
point
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
FF2
Focal length
Focus
2 x focal length
F1F2
Focal length
Focus
Focal length
2 x focal length
F1F2
Focus
Focal length
2 x focal length
F1F2
Focal length
Focus
Focal length
2 x focal length
F1F2
Focal length
Focus
Focal length
2 x focal length
F1F2
Focal length
Focus Focus
Focal length
2 x focal length
F1F2 F1
Focal length
Focus Focus
Focal length
2 x focal length
F1F2 F1
Focal length
Focus Focus
Focal length
2 x focal length
F1F2 F1
Focal length
2 x focal length
Focus Focus
Focal length
2 x focal length
F1F2 F1
Focal length
2 x focal length
Focus Focus
Focal length
2 x focal length
F1F2 F1 F2
Focal length
2 x focal length
Focus Focus
F1 F1F2 F2
Object located beyond 2 focal
lengths (F2)
F1 F1F2 F2
Light rays converge at this point.
F1 F1F2 F2
A real image is formed. A real image
can be projected onto a screen.
F1 F1F2 F2
A real image is formed. A real image
can be projected onto a screen.
The image is inverted (up-side down) and
smaller than the original object.
F1 F1F2 F2
When the object is located beyond 2 focal
lengths (F2)
F1 F1F2 F2
When the object is located beyond 2 focal
lengths (F2)
The image created is real, inverted and smaller than the original object.
F1 F1F2 F2
When the object is located beyond 2 focal
lengths (F2)
The image created is real, inverted and smaller than the original object.
The rays converge between 1 and 2
focal lengths
F1 F1F2 F2
Other rays can be added from different points on the object
F1 F1F2 F2
These extra rays all converge at the same point between 1 and 2
focal lengths.
F1 F1F2 F2
These extra rays are unnecessary for our
purposes.
F1 F1F2 F2
Draw rays only from the top point of your object.
This will keep your diagram simple and easy to understand