Curved Mirrors
2 Types:
1. Converging Mirrors
2. Diverging Mirrors
Terms
• mirror is part of an imaginary sphere
Centre of Curvature (C) – the centre of the
sphere
Vertex (V) – point where the C meets the
centre of the mirror
Principal Axis (P) – line between the C and V,
forms a right angle with the mirror
Converging Mirrors
(Concave)
• edges curve towards you
• eg. make-up/shaving mirrors
• all light rays parallel to principal axis converge
(meet) at one point (focus)
• Focus (F) – is halfway between V and C
principal axis
centre of
curvature
vertex
Drawing Ray Diagrams
for Converging Mirrors
• an image forms when the rays come together at F
• if they do not converge (meet) there is no image
• there are 4 rules to locating objects in converging
mirrors:
A light ray parallel to the principal axis is reflected
through the focus. This is how the focus is defined.
A light ray through the centre of curvature is reflected
back onto itself.
A ray through F will reflect parallel to the principal axis.
A ray aimed at the vertex will follow the law of reflection
Reflection From Curved Surfaces
SALT of Converging Mirrors
1
2
3
4
5
Applications of
Converging Mirrors
• show things up closely
(makeup/shaving mirrors)
• Solar Cookers – focuses rays on one
point in order to cook food
• Early Reflecting Telescopes –
capture light from outer space to
meet at F
• http://astrocanada.ca/_en/a2304.html
• Hubble Telescope – in use today
• HubbleSite - Two Decades Unveiling
the Universe
2. Diverging (Convex) Mirrors
• edges are thicker than centre of mirror
• show a wide area (eg. store security mirrors)
• light rays diverge (spread apart) after they hit the
mirror
Locating Images in Diverging Mirrors
• light rays always diverge after they strike a diverging
mirror
• similar rules to converging mirrors
• C and F are located behind the mirror
Drawing Ray Diagrams for
Diverging Mirrors
1. Draw the incident ray from the object to the mirror
following one rules above.
2. Draw the reflected ray.
3. Extend the reflected ray beyond the mirror using a
dotted line.
4. Repeat for another light ray.
5. Find the location of the image where the dotted
lines cross.
SALT of Diverging Mirrors
S – smaller
A – upright
L – behind mirror
T – virtual
*always same no matter of objects location to
mirror
Characteristics of Images Formed by Mirrors