LIGHT AND COLOUR

http://micro.magnet.fsu.edu/primer/java/reflection/index.html

LINK TO INTERACTIVE SITE – CLICK HERE

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

http://micro.magnet.fsu.edu/primer/java/mirrors/concave.html

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.

Molecular Expressions Microscopy Primer: Light and Color - Concave Mirrors: Interactive Java Tutorialhttp://micro.magnet.fsu.edu/primer/java/mirrors/convex.html

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.

• 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.

http://micro.magnet.fsu.edu/primer/java/refraction/index.html

http://micro.magnet.fsu.edu/primer/java/variablelens/index.html

Total internal reflectionand 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.

CLICK HERE FOR INTERACTIVE SITE http://micro.magnet.fsu.edu/primer/java/refraction/fishtank/index.html

White light is made up of the seven colours of the rainbow.

Red, orange, yellow, green, blue, indigo, and violet.

Molecular Expressions Microscopy Primer: Light and Color - Refraction of Light

Molecular Expressions Microscopy Primer: - Light and Color - Additive Primary Colors

Molecular Expressions Microscopy Primer: Light and Color - Subtractive Colors

How We See Colour

• We see colours because those are refelected off and object. Yellow light is refelected to our eyes but the other colours are absorbed so we see yellow.

RAINBOWS• We see rainbows because

the light is first refracted by the raindrop and then reflected off the back of the raindrop.

MIXING COLOURS• When we mix the three primary

colours of light we get white light. RED GREEN BLUE

• If we mix the three secondary colours of light we get black CYAN MAGENTA YELLOW

Molecular Expressions Microscopy Primer: Light and Color - Color Filters: Interactive Java Tutorial

In white light in red light in green light in blue light this is what the grapes and card will look like

In these glasses only light perpendicular to the highway is allowed through. This halves the amount of light reachingthe eye.

THE EYE

• The pupil allows light to enter the eye.• The lens helps to focus the light• Light sensitive cells in the retina detect the

light.• A nerve impulse travels from the retina to

the brain along the optic nerve where it is interpreted.

• The iris helps to change the size of the pupil

Molecular Expressions Microscopy Primer: Light and Color - Human Vision: Interactive Java Tutorial

http://cse.ssl.berkeley.edu/light/program.html

CLICK HERE TO INVESTIGATE REFRACTION IN A PRISM http://micro.magnet.fsu.edu/primer/java/prismsandbeamsplitters/equilateralprism/index.html