Light Notes 4Lenses and Mirrors

Regular Reflection-

• Light waves hit a smooth surface and bounce off (reflect) at the same angle

• Angle of incidence = _________________

• Gives ____________ image.

.

Angle of reflection

sharp

Diffuse Reflection

• When light waves hit a surface and bounce off at different angles

• Angle of incidence __________________

• Gives _______ image. Law of Reflection –

= angle of reflection

fuzzy

Angle of incidence = angle of reflection

Mirrors and Lenses

• Mirror – opaque material that reflects light

• Lens – transparent material that refracts light

Concave and Convex Lenses

Concave lens

Curves inward

light separated

used in hotel peep holes

• Convex Lens

• curves outward

•Light brought together

• magnifying glass

Concave Mirror

• has a reflecting surface that bulges inward (away from the incident light). Concave mirrors reflect light inward to one focal point, therefore they are used to focus light. Unlike convex mirrors, concave mirrors show different types of image depending on the distance between the object and the mirror itself.

used in headlights of vehicles to send parallel rays to infinity , in shaving mirror to get an enlarged image of the face and also by dentists to see a bigger image of the tooth / teeth

Convex Mirror• The passenger-side mirror on a car is typically a convex mirror. In

some countries, these are labeled with the safety warning "Objects in mirror are closer than they appear", to warn the driver of the convex mirror's distorting effects on distance perception.

• Convex mirrors are used in some automated teller machines as a simple and handy security feature, allowing the users to see what is happening behind them. Similar devices are sold to be attached to ordinary computer monitors.

curved mirror in which the reflective surface bulges toward the light source. Convex mirrors reflect light outwards, therefore they are not used to focus light.

Mirrors VS Lenses

• Convex mirrors cause light to spread out, concave mirrors cause light to go in and create a focal point. But lenses work the opposite way: concave lenses spread the light out, convex lenses focus the light. WHY IS THAT? Why don’t they work in the SAME way as mirrors, instead of the opposite way?

The reason that mirrors and lenses behave so differently is that light passes though lenses but bounces off mirrors.

Virtual Image

• What you see when you look in a mirror.

Real Image

• an image that can be projected onto a screen