curved mirrors. types of curved mirrors: concave mirror –a mirror whose reflecting surface curves...

Curved MirrorsCurved Mirrors

Types of curved mirrors:Types of curved mirrors:

Concave mirrorConcave mirror– A mirror whose reflecting A mirror whose reflecting

surface curves inward – surface curves inward – Converging mirrorConverging mirror

Convex mirrorConvex mirror– A mirror whose reflecting A mirror whose reflecting

surface curves outward – surface curves outward – Diverging mirrorDiverging mirror

DefinitionsDefinitions

Center of Curvature (C)Center of Curvature (C)– Center of a sphere whose surface has been Center of a sphere whose surface has been

used as a mirrorused as a mirror

C = 2fC = 2f

Principal axis (P.A.)Principal axis (P.A.)– The line through C that passes through the midpoint of the The line through C that passes through the midpoint of the

mirror (normal to the centre of the mirror)mirror (normal to the centre of the mirror)

Vertex (V)Vertex (V)– The point where the P.A. meets the mirrorThe point where the P.A. meets the mirror

Focal Point (F)Focal Point (F)– Is halfway between the vertex and the center of curvature. Is halfway between the vertex and the center of curvature.

When parallel light rays are shone along the P.A., the When parallel light rays are shone along the P.A., the reflected rays converge and cross at the focal point.reflected rays converge and cross at the focal point.

Focal length (f)Focal length (f)– The distance from the focal point to the vertexThe distance from the focal point to the vertex

ConvergeConverge– To meet at a common pointTo meet at a common point

Rules for the construction of ray Rules for the construction of ray diagrams:diagrams:

1.1. Parallel rays are reflected through FParallel rays are reflected through F

2.2. Rays passing through F are reflected Rays passing through F are reflected parallel to the P.A.parallel to the P.A.

3.3. Rays passing through C are reflected Rays passing through C are reflected back along the same pathback along the same path

4.4. Rays striking V follow the laws of Rays striking V follow the laws of reflection (angle of incidence = angle of reflection (angle of incidence = angle of reflection)reflection)

Ray Diagrams are used to find the Ray Diagrams are used to find the Image of an ObjectImage of an Object

How to draw a Ray Diagram for a How to draw a Ray Diagram for a concave mirrorconcave 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.


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.


3. Draw the first Ray from the top of the object parallel to the P.A. Its reflecting ray will pass through F.


4. Draw the second ray from the top of the object through F, its reflecting ray will travel parallel to the P.A.



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)



6. Draw the top of the image where the reflective rays intersect. The bottom of the image will be at the P.A.


**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.


What is the LOST for this image?


What is the LOST for this image?L – in front of the mirror (b/w C and F)O – invertedS – smallerT - real

Time to Practice!!Time to Practice!!

Complete the remainder of the Ray Complete the remainder of the Ray Diagrams on your worksheetDiagrams on your worksheetIdentify the LOST for eachIdentify the LOST for eachComplete the “Discovery Stations” – taking Complete the “Discovery Stations” – taking down appropriate info and observations as down appropriate info and observations as you goyou go

Homework:Homework:Read text p.496-500Read text p.496-500Do Questions p. 501#1, 2, 5, 8a,bDo Questions p. 501#1, 2, 5, 8a,b

Worksheet Ray Diagrams #2Worksheet Ray Diagrams #2

L – in front (outside C)O – invertedS – largerT - real


L – at CO – invertedS – sameT - real


Ray 4 – strikes at V and angle i = angle r

L –O –S –T -… NO IMAGEReflective rays are parallel


L – behind mirrorO – uprightS – largerT - virtual

Uses of concave mirrorsUses of concave mirrors

Satellite DishesSatellite Dishes

Solar cookersSolar cookers


lasers, flashlights, car lasers, flashlights, car headlightsheadlights


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


TelescopesTelescopes

Sir Isaac Newton(1643–1727), developed one of the first reflector telescopes in 1668. Reflector telescopes are still used today, mainly in the field of astronomy.

curved mirrors. types of curved mirrors: concave mirror –a mirror whose reflecting surface curves...

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