Light PS 9 Light Waves Electromagnetic waves Combination

Light PS 9

Light Waves • Electromagnetic waves – Combination of electric and magnetic fields – Do not require a medium to travel through – Electromagnetic waves are transverse waves – Travel at 300, 000 m/s (3 x 108 m/s)

Light can… • pass through anything that is transparent • pass partially through anything that is translucent • not pass through things that are opaque.

Light Waves • Wavelength – Measures the distance from crest to crest or trough to trough – Wavelength determines the color of the light • Frequency – Measures the amount of waves that pass a point per second (Hz)

Light Waves • Amplitude – Measures the distance from the rest position to a crest or trough – Amplitude is the brightness of the light • Speed – How far a wave travels in one unit of time

Light Waves • Formulas – Speed = wavelength x frequency – Frequency = speed ÷ wavelength – Wavelength = speed ÷ frequency As wavelength increases, frequency decreases As frequency increases, wavelength decreases

Reflection • Reflection – A wave hits a surface through which it cannot pass; it bounces back – Usually happens on opaque objects, but can also happen on translucent and transparent objects

Specular Reflection • Reflection on a smooth surface

Diffused Reflection • Reflection on an uneven surface

Reflection • Plane Mirror: flat mirror that forms an image that is always right side up, same size as the real object, and same distance away from the mirror as the real object

Reflection • Concave mirror: mirror that curves inward that forms images depending on the object’s position from the mirror. • Ex: make-up mirror, flashlights, car headlights, telescopes

Concave Mirror • Object farther away = image upside down and smaller • Object medium distance away = image upside down and larger • Object close = image right side up and larger

Reflection • Convex mirror: mirror that curves outward and forms images that are always right side up and appear smaller and farther away than they really are.

Convex Mirror Examples

Refraction • Refraction – The bending of waves due to change in speed – If white light is bent it turns into the visible spectrum – If the visible spectrum is bent it turns back to white light

Refraction • Concave lens a lens that curves inward and creates an image that spreads light to produce an image that is right side up

Concave Lens

Refraction • Convex lens: a lens that curves outward, directing light to a center focal point

Refraction • Object farther away = images upside down and smaller • Object medium distance away = image upside down and larger • Object close up = image upright and large

Seed Pod Before Seed Pod Viewed through a Convex lens at a medium distance Convex Lens Used close up

Diffraction • The bending of waves around the edge of a barrier

Interference • Two waves meet • Constructive • Destructive