Flat & Curved Mirrors

Normal Line

Terminology of Reflection

Incident Ray Reflected Ray

<i <r

<i = <r

1. <i is equal to <r

2. Incident ray, reflected ray and the normal all lie in the same plane.

Laws of Reflection

mirror

Locating an image in Flat MirrorCan use equidistance property as an easy

way to locate image in flat mirrors

Size Smaller vs. Same vs. Larger

Attitude Upright vs. Inverted

Location Where the image is locatedType Real (image on same side as object) vs. Virtual (image is behind

mirror)

SALT

Concave MirrorsLocating images

Applications

1st: Draw a straight principal axis2nd :Pick a point as your Vertex (V)3rd : Pick a point as your Centre (C)4th: F = ½ C5th: Use your compass to draw the lens

Drawing Concave Mirror template

VFC

Incident rays entering to a “Cave” Concave = converging

Concave Mirrors - Rules

C VFPrincipal axis

A ray parallel to principal axis is reflected through the focal point

A ray going through the focal point is be reflected parallel to the principal axis

A ray going through the centre of curvature (C) is reflected back through C

A ray going through the vertex is reflected at the same angle (<i = <r)

Image on SAME SIDE as object = REAL Image (can be captured on “screen”)

Image behind the mirror = VIRTUAL Image

Concave Mirrors – Real vs. Virtual Image

Object

REAL Image

VIRTUALImage

Simply use 2 of the rules If object is Beyond C:

Concave Mirrors – Finding the Image

C VF

Image is:S – smallerA – invertedL – between C&FT – Real image

If object is at C

Concave Mirrors – Finding the Image

C VF

Image is:S – same sizeA – invertedL – At CT – Real image

If object is between C & F

Concave Mirrors – Finding the Image

C VF

Image is:S – largerA – invertedL – Beyond CT – Real image

If object is at F:

Concave Mirrors – Finding the Image

F VC

Parallel lines do not meet up

NO clear image

If object is between F and V:

Concave Mirrors – Finding the Image

F VC Image is:S – largerA – uprightL – behind mirrorT – Virtual image

Concave Mirrors animation

Solar cooker parallel beams of light from the Sun will converge at focus (F)

Others: convergence of signals on satellite dish

Applications of Concave Mirror

Search light need parallel beams of light

Set filament at focus (F)

Applications of Concave Mirror

Convex MirrorsLocating images

Applications

Rays ”bouncing off a ball” Convex = diverging

Convex Mirrors - Rules

V F

Principal axis

C

1st: A ray parallel to p.a. is reflected AS IF it had come through F2nd: A ray AIMED at C is reflected back upon itself.

3rd: A ray AIMED at F is reflected parallel to p.a.

Incident rays ”bouncing off a ball” Image is ALWAYS smaller and virtual

Convex Mirrors – Finding the Image

V F C

Important Step!! Extend line backward.

Convex Mirror animation

Security mirror convex mirrors show a wide range of view with their smaller virtual image.

Applications of Convex Mirror