Properties of Light

Properties of Light

By Abby Fancsali

Reflection of Light-Light Bouncing off a Barrier

• Light is reflected when it bounces off of some medium

• Law of Reflection: light reflects off of an object at the same angle it hits the object​

  • Occurs on all surfaces

  • Angle of reflection = the angle of Incidence

    • Notice how some of the lines seem to emanate from behind the mirror​

    • A reflected image in a mirror is the same distance away from the mirror as the object in front of the mirror

• Reflections have the frequency of the light waves that strike them, shown by reflections have the same color as the original object

Types of Mirrors

• Plane Mirror: A flat mirror

  • Images look the same size as the object being reflected

• Curved Mirrors: images look different sizes based on how the mirror is curved​

Multiple Choice

How do you know reflected waves have the same frequency as the original wave?

• Reflected objects are the same size

• Reflected objects are the same color

• Reflected objects have shadows

• You can't tell

Diffuse Reflection

• Diffuse Reflection: light hitting a rough surface and reflecting in many directions

  • A polished surface has microscopic differences on the surface of an object

    • Objects can be polished to work best for different waves​

  • Allow people to see objects without a glare

    • Most of our vision of the environment occurs through Diffuse Reflection

Multiple Choice

The law of Reflection can be applied to ______

• Flat surfaces

• Curved Surfaces

• Horizontal Surfaces

• All Surfaces

Refraction-The Bending of Light as its Speed Changes

• Recall-Light slows down as it enters glass/transparent materials

  • Light travels at different speeds in different materials

• Refraction is the bending of light as it travels between mediums

  • Bending occurs when light is not perpendicular to the surface of penetration​

  • Can cause illusions and mirages

Diffraction-The Spreading of Light

• Diffraction-the bending of light by means other than reflection and refraction

  • Occurs as light passes through small openings or around the edge of surfaces

  • Causes problems with microscopes, where small objects can be close to the size of the wavelengths

    • Electron microscopes use much smaller wavelengths that fix this problem​

Interference of Light Waves and Iridescence

• Interference is a property of all waves, including light waves

  • Waves of the same frequency can add together​ and produce a wave of the same frequency with twice the amplitude

  • Waves of inverse frequency cancel out

    • Can lead to iridescence in objects

      • ​one color is canceled by interference and the complementary color is seen

Wave-Particle Duality

• Light is made up of small particles known as Photons

• Light behaves as a wave when traveling from sources, and as photons when interacting with detectors​

Multiple Choice

What is the return of light into the medium it came from

• Reflection

• Refraction

• Diffraction

• Interference

Multiple Choice

What is True about the speed of light

• It is constant in all materials

• It can change when light passes from one medium to another

• It is higher in a more dense medium