Download Concave and Convex Mirrors and Lenses

Concave and Convex Mirrors and Lenses
What do you
notice about the
letters painted
on this
emergency
vehicle?
Today, I can describe images formed by
concave and convex mirrors and lenses.
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Use ray diagrams to show how light is reflected or refracted
Compare plane mirrors, concave mirrors, and convex mirrors
Use ray diagrams to show how mirrors form images
Describe the images formed by concave and convex lenses
Concave and Convex Mirrors and Lenses
Remember the emergency
vehicle? The letters appear
backwards and spells ambulance
when someone sees it from
their rearview mirror.
Rays and the Path of Light Waves
• Light waves are electromagnetic waves
• Light waves travel from their source in all directions.
• A ray can be used to show the path and direction of a light wave
after it bounces or bends.
• Light waves that bounce off an object are reflected.
• Light waves that bend when passing from one medium to another
are refracted.
Mirrors and Reflection
• The shape of a mirror affects the way that light reflects from it.
• There are 3 types of mirrors … classified by their shape:
• Plane Mirror
• Concave Mirror
• Convex Mirror
Plane Mirror
• A mirror with a flat surface that can only form virtual images.
• Images are reversed left to right.
• When you look in a plane mirror, your reflection is right size
up.
• Your reflection is the same size as you are.
• Your bathroom mirror and the rearview mirror in car are
examples of a plane mirror.
How are images formed in plane mirrors?
Concave Mirrors
• Images formed depend on the optical axis, focal point, and
focal length or the mirror.
• Form virtual images and real images.
• A real image is an image through which light passes. A
real image can be projected on a screen but a virtual image
cannot.
• Concave mirrors are used in car headlights and
flashlights.
Images from Concave Mirrors
• To find out what kind of image a concave mirror forms, you can make
a ray diagram.
• If the reflected rays cross in front of the mirror, a real
image is formed.
• If the reflected rays do not cross in front of the mirror,
extend the reflected rays in straight lines behind the mirror
to see where the virtual image is formed.
Images from Concave Mirrors
• No image will form when an object is placed at the focal point of a
concave mirror.
• All rays that pass through the focal point on their way to the mirror will reflect
parallel to the optical axis.
• The rays will never cross in front or behind the mirror.
• If you put a light source at the focal point of a concave mirror,
light will reflect outward in a powerful beam.
• This is why concave mirrors are used in headlights and flashlight.
Concave Mirrors
Concave Mirror
Convex Mirrors
• A mirror that curves outward.
• Reflected rays do not cross in front of the mirror, but extend
behind the mirror to show a virtual image.
• All images formed by convex mirrors are virtual, right side
up, and smaller than the original object.
• Convex mirrors are useful because they make images of large
areas.
Convex Mirrors
• The back of a spoon is an example of a convex mirror.
• When you look at yourself in the back of a spoon, you
will notice that your image is small and right side up.
• Convex mirrors are used for security in stores and factories.
• Convex mirrors are used as side mirrors on cars and trucks.
Convex Mirrors
Lenses and Refraction of Light
• A lens is a transparent object that forms an image by refracting, or bending
light. They have a focal point and an optical axis.
• Lenses are classified by their shape.
• There are two types of lenses
• Convex Lens
• Concave lens
Convex and Concave Lenses
Convex Lens
• Lens that is thicker in the middle than at the edges.
• Can form a real image that is larger than the object
if the object is between 1 and 2 focal lengths away
from the lens.
• Magnifying lenses and camera lenses are convex
lenses. They can also be used in eyeglasses.
Convex Lens
Concave Lens
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Lens that is thinner in the middle than at the edges.
Never form a real image.
Always form a virtual image.
Can be combined with other lenses in telescopes.
Used in microscopes and eyeglasses.
Concave Lens
EXIT TICKET
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5.
Explain the difference between a convex mirror and a concave mirror.
How do convex lenses and concave lenses differ?
Name two things that form real images.
Name two things that form virtual images.
Give 3 examples of how mirrors and lenses are used in our lives.