Properties of Light

Electromagnetic Spectrum

What is Light?

• Light is a type of wavewave that carries energy through matter or spacematter or space.

• A source of energy such as the Sun or a light bulb gives off light waves that spread out in all spread out in all directionsdirections from the light source.

• A light raylight ray is a narrow beam of light that travels in a straight line.

Light Travels Through Space

• The material through which a wave travels is called the mediummedium.

• Light is an electromagnetic waveelectromagnetic wave and doesn’t need a medium in which to travel.

• Electromagnetic waves can travel in a vacuum, as well as materials such as air, water, and glass.

Light and Matter• Most objects can only be seen if light waves from

another sourceanother source bounce off of them and into your eyes.

• The process of light striking an object and bouncing off is called reflectionreflection.

• When light waves strike an object, some of the waves are absorbedabsorbed by the object, some are reflectedreflected by it, and some might pass through itpass through it.

• What happens to light when it strikes an object depends on the materialmaterial the object is made of.

Opaque, Translucent, and Transparent

• All objects reflect and absorbreflect and absorb some light waves.

• Materials are opaque, translucent or transparent depending on how much light how much light passes through thempasses through them.

• Which type of material reflects the least amount of light?

• Transparent MaterialsTransparent Materials

Opaque, Translucent, and Transparent

• Materials that do not let light pass through them are opaqueopaque.

• You cannot seecannot see other objects through opaque materials.

• Some examples include:– WallsWalls– DesksDesks– Most ObjectsMost Objects

Opaque, Translucent, and Transparent

• Materials that allow nearly all lightall light that strikes them to pass though are transparenttransparent.

• You can clearly see thoughcan clearly see though these types of object.

• Some examples include?:• Glass and clear plasticGlass and clear plastic.

Opaque, Translucent, and Transparent• TranslucentTranslucent materials allow only some light to

pass through.• Although object behind these materials are

visible, they are not clearnot clear.• Some examples include?:• Frosted glass andFrosted glass and• Wax paperWax paper.