Curved Mirrors

1. Curved Mirrors Samantha Nelson Mrs. Grayot Physics Per. 6 March 2, 2009

2. Definition • A Curved Mirror is a reflective surface that is a segment cut from a sphere or a parabola. • Spherical: a mirror whose reflecting surface is cut from the inward or outward curve of a sphere. • Parabolic: a segment of a paraboloid.

3. Points of a Mirror • Principal Axis: line passing through the center of the sphere and attaching to the mirror in the exact center of the mirror. • Center of Curvature: a point in the center of the sphere from which the mirror was cut. • Vertex: a point on the mirror's surface where the principle axis meets the mirror. The geometric center of mirror. • Focal Point: A point halfway between the vertex and the center of curvature. • Law of Reflection: Angle of incidence equals angle of reflection.

4. Spherical Mirrors • A circular mirror that has the shape of part of a sphere’s surface • Two Types • Convex • Concave

5. Convex • Bulging outward or diverging • Segment of the circle that is silvered on the outside of the curve • The center is the point closest to viewer • Reflects Light outwards • Does not focus light • Forms only virtual images and has a negative focal length and image distance. • The image produced is always diminished and upright

6. Concave • Bulging inward or converging • Center is farthest away from viewer • Reflects light inward to focal point • Focuses Light • Used to form larger or smaller images of object • Which image that is produced depends on the radius of the curvature of the mirror • Image produced depends on the distance between the object and the viewer and the mirror’s surface. • Produces virtual and real images • Images are can be larger, smaller, right-side up, or upside down

7. Virtual and Real Images • Virtual Images • An image in which outgoing rays from a point on the object will never actually intersect at a point. • The image is seen within or behind the mirror • Real Images • Images of light that can be projected on a screen and are always upside down or inverted. • Images existing outside the mirror

8. Image Location • The location of an image depends on the object’s distance from the mirror, image distance, and the radius of the curvature of the mirror. • Image location can be predicted using an equation • 1/p + 1/q= 1/f • 1/Object distance+1 / image distance = 1/focal length

9. Magnification • How large or small the image is in the mirror. • M = h’/h = -q/p • Magnification=image height/object height Or Magnification= - image distance/object distance • M> 1 then image is larger than object • M< 1 then image is smaller than object • M is + then image is virtual and upright • M is – then image is real and inverted or upside down

10. Spherical Aberration • Spherical mirrors suffer from spherical aberration. • It is when rays that are reflected off the surface of the mirror do not intersect exactly at the image point. • Causes fuzzy and blurred images • It occurs in mirrors where light rays strike the surface far from the principle axis. • It is present to some extent in every spherical mirror but is most noticeable in Concave mirrors

11. Parabolic Mirrors • Segments of a paraboloid, a three dimensional parabola. • Inner surface reflects • Used to reduce spherical aberration • Reduce the diameter, reduce aberration • Used commonly in astronomical telescopes because it produces a clearer image then the concave spherical mirror, yet still collects the same amount of light.