Curved Mirrors

Types of curved mirrors: Concave mirror –A mirror whose reflecting surface curves inward – Converging mirror Convex mirror –A mirror whose reflecting surface curves outward – Diverging mirror

Definitions Center of Curvature (C) –Center of a sphere whose surface has been used as a mirror C = 2f

Principal axis (P.A.) –The line through C that passes through the midpoint of the mirror (normal to the centre of the mirror) Vertex (V) –The point where the P.A. meets the mirror Focal Point (F) –Is halfway between the vertex and the center of curvature. When parallel light rays are shone along the P.A., the reflected rays converge and cross at the focal point.

Focal length (f) –The distance from the focal point to the vertex Converge –To meet at a common point

Rules for the construction of ray diagrams: 1. Parallel rays are reflected through F 2. Rays passing through F are reflected parallel to the P.A. 3. Rays passing through C are reflected back along the same path 4. Rays striking V follow the laws of reflection (angle of incidence = angle of reflection)

Ray Diagrams are used to find the Image of an Object

How to draw a Ray Diagram for a concave mirror 1. Draw a horizontal line (P.A). Mark a Center of curvature, C, and draw a curve using a compass. Mark focal point, F, half way between C and V.

How to draw a Ray Diagram for a concave mirror 2. Draw the object with its base on the P.A. 1. Draw a horizontal line (P.A). Mark a Center of curvature, C, and draw a curve using a compass. Mark focal point, F, half way between C and V.

How to draw a Ray Diagram for a concave mirror 3. Draw the first Ray from the top of the object parallel to the P.A. Its reflecting ray will pass through F.

How to draw a Ray Diagram for a concave mirror 4. Draw the second ray from the top of the object through F, its reflecting ray will travel parallel to the P.A. 3. Draw the first Ray from the top of the object parallel to the P.A. Its reflecting ray will pass through F.

How to draw a Ray Diagram for a concave mirror 4. Draw the second ray from the top of the object through F, its reflecting ray will travel parallel to the P.A. 5. Draw a third ray through C, it will reflect back upon itself (because it is a normal) 3. Draw the first Ray from the top of the object parallel to the P.A. Its reflecting ray will pass through F.

How to draw a Ray Diagram for a concave mirror 6. Draw the top of the image where the reflective rays intersect. The bottom of the image will be at the P.A.

How to draw a Ray Diagram for a concave mirror **Note: you only need 2 intersecting Rays in order to find the image** 6. Draw the top of the image where the reflective rays intersect. The bottom of the image will be at the P.A.

How to draw a Ray Diagram for a concave mirror What is the LOST for this image?

How to draw a Ray Diagram for a concave mirror What is the LOST for this image? L – in front of the mirror (b/w C and F) O – inverted S – smaller T - real

Time to Practice!! Complete the remainder of the Ray Diagrams on your worksheet Identify the LOST for each Complete the “Discovery Stations” – taking down appropriate info and observations as you go Homework: Read text p Do Questions p. 501#1, 2, 5, 8a,b

Worksheet Ray Diagrams #2 L – in front (outside C) O – inverted S – larger T - real

Worksheet Ray Diagrams #3 L – at C O – inverted S – same T - real

Worksheet Ray Diagrams #4 Ray 4 – strikes at V and angle i = angle r L –O –S –T -… NO IMAGE Reflective rays are parallel

Worksheet Ray Diagrams #5 L – behind mirror O – upright S – larger T - virtual

Uses of concave mirrors Satellite Dishes Solar cookers

Uses of concave mirrors lasers, flashlights, car headlights

Uses of concave mirrors Radar detectors – concave mirror in shape (generator and detector are at focal point)

Uses of concave mirrors Telescopes Sir Isaac Newton(1643–1727), developed one of the first reflector telescopes in Reflector telescopes are still used today, mainly in the field of astronomy.