Curved Mirrors • Curved mirrors are like plane mirrors • they too have smooth, shiny surfaces that reflect light. • The surface can either curve in (concave) or out (convex) as shown below
Dec 22, 2015
Curved Mirrors• Curved mirrors are like plane mirrors • they too have smooth, shiny surfaces that reflect
light. • The surface can either curve in (concave) or out
(convex) as shown below
Concave mirrors
They curve inwards
They can form two types of image
If the light rays come from something close, the
image is upright and magnified
It is a virtual image
If the light rays come from something distant, they
come to a focus after reflection
They converge (come together) to form a small inverted image which can be picked up on a screenThe type of image is called a real imageThe rays of light actually meet to form it.
Converging mirror
Rays from very distant things are nearly parallel to
each other
a concave mirror brings parallel rays to a focus at a
point called the principal focus (F)
the distance from the mirror to the principal focus is
called the focal length
highly curved mirror have short focal lengths
Remember, the concave mirror is part of a sphere
The centre of curvature of a mirror is the centre of the
sphere part of whose surface forms the curved mirror
It is labelled C
The principal axis of the mirror is the line going through the centre of curvature and the centre of the mirror
V
The point on the mirror's surface where the principal axis meets the mirror is known as the vertex and is denoted by the letter V in the diagram . The distance from the vertex to the center of curvature is known as the radius of curvature (represented by R). The radius of curvature is the radius of the sphere from which the mirror was cut. Since the focal point is the midpoint of the line segment adjoining the vertex and the center of curvature, the focal length would be one-half the radius of curvature.
How to locate the image in Converging (Concave) Mirror
To determine the image of an object in front of a concave mirror,
you need to draw at least two incident rays from the top of the object
these rays will be reflected off the mirror and may not cross to form an image
Drawing an image on Concave mirror
Using three kinds of rays1. The ray parallel to principle axis is reflected
through the focal point (F)
2. The ray passing through F is reflected parallel to the principle axis
3. The ray passing through the center of curvature C is reflected along its same path through C
Convex Mirror
Characteristic of convex mirror
1. A convex mirror is part of the outer surface of
a hollow sphere
2. A convex mirror produces diverged rays
3. A convex mirror does not form real images
4. Convex mirror in daily life, used in cars, and
used in stores to observe shoppers.