Reflection and Refraction

Angle of incidence = angle of reflection

THE LAW OF REFLECTION The angle of incidence is equal to the angle of reflection. The image in a plane mirror is virtual and is the same size as the object. Plane mirrors are used in periscopes. They are used in rear view mirrors. The image is as far behind the mirror is as the object is in front. Image is laterally inverted

PERISCOPES

Shiny smooth surfaces reflect regularly, other surfaces also reflect light but if the surface is rough the light is reflected in all directions. We call this diffuse reflection.

Diffuse Reflection

CONVEX AND CONCAVE MIRRORS

Convex and Concave Mirrors A concave mirror is a converging mirror. Parallel rays of light are reflected through the focal point of a concave mirror. A convex mirror is a diverging mirror. Parallel rays of light are reflected so that they appear to come from the focal point of a convex mirror.

Uses of Concave Mirrors Used to collect light energy, sound, heat, radiation, radar and TV signals. If you move close to a concave mirror, then you see a magnified image of yourself. This image is upright and virtual as well as magnified. Shaving and make up mirrors

Uses of Convex Mirrors They always produce virtual upright images. The image is always smaller than the object. They are useful when you want a wide field of view – car driving mirrors or shop security.

Refraction This is the bending of light rays Happens because the rays change speed. When they enter a more dense medium (glass, water,) they slow down. When they enter a less dense medium – like air, they speed up.

Total internal reflection and refraction When an object is viewed through water the image we see is changed because of the way light waves behave as they pass from the water into the air.