1. Spherical Mirrors
A spherical mirror has the shape of a section of a sphere
The mirror focuses incoming parallel rays to a point (focal point)
A concave spherical mirror has the silvered surface of the mirror on the inner, or concave, side of the curve
A convex spherical mirror has the silvered surface of the mirror on the outer, or convex, side of the curve

2. Convex vs Concave
focal points

3. Types of Images
A real image is formed when light rays pass through and diverge from the image point
Real images can be displayed on screens
A virtual image is formed when light rays do not pass through the image point but only appear to diverge from that point
Virtual images cannot be displayed on screens

4. Mirror lens equation do = object distance ( always +)
di = image distance (+ for real images; ▬ for virtual images)
f = focal length (+ concave mirror; ▬ convex mirror)

5. Magnification Magnification, M, is defined as
This is the general magnification for any type of mirror
It is also valid for images formed by lenses
Magnification does not always mean bigger, the size can either increase or decrease
M less than 1  image size decreased
M greater than 1  image size increased

6. Ray Tracing c f
Parallel ray hits the mirror and reflects through the focal point
Ray through focal point hits the mirror and reflects parallel

7. Ray Tracing f c
Parallel ray hits the mirror and reflects as if it started at the focus
Ray heading to the focus hits the mirror and comes off parallel

8. Find the image characteristics
f = 20 cm
do = 32 cm
real,
inverted,
larger c f or 1 1 1 1 1 1 = + = + 20 f do di 32 di
di = + 53 cm
real,
inverted,
larger di 53
M = –
= – = do 32

9. Mirror Cases CONCAVE c f
– object beyond c
Image – real, inverted, smaller, between c and f
– object at c
Image – real, inverted, same size, at c
– object between c and f
Image – real, inverted, larger, beyond c
– object between f and v
Image – virtual, upright, larger, behind mirror
CONVEX f c
– object anywhere
Image – virtual, upright, smaller, behind mirror