Interference Chapter 15 Section 1
Terms to know • Coherence • The correlation between the phases of two or more waves • Path Difference • The Difference in the distance traveled by two beams when they are scattered in the same direction from different points • Order Number • The number assigned to interference fringes with respect to the central bright fringe • Fringe • A light or dark band made by the interference of light. • Interference • The addition or coming together of several waves (can be light, sound, or water waves). • Light • Electromagnetic radiation visible to the human eye. • Wave Crest • The top or high point of a wave. • Wave Trough • The bottom or lowest point of a wave.
Light travels in waves. • Interference-is the interaction between waves traveling in the same medium. • When two waves come into contact constructive and destructive interferences will occur depending on the phase differences of the waves. • Two set of waves (such as light) can combine with each other to produce a resultant wave. The way in which this combined wave is produced is called interference.
In constructive interference the amplitude (height) of the wave is amplified. The crest of the two waves will be added together to get the resulting amplitude of the two waves combined. After the two waves have passed each other they go back to normal. • Constructive Interference happens when two or more waves come together to form a larger and stronger wave, matching their crests and troughs. Wave 1 Wave 2 Result
Destructive interference is a lot like constructive interference but instead of adding the two wave crest together you subtract them. This happens when the two waves are out of phase. Just like constructive interference once the waves are past each other they resume their original amplitude. Destructive Interference is when two or more waves come together and cancel each other out to make a weaker wave. Wave 1 Wave 2 Result
Light waves interfere to form bands of color on a soap bubble’s surface
Colors of peacock feathers are caused bylight reflected from complex layered surface
Sound Interference • If you strike a tuning fork and rotate it next to your ear, you will note that the sound alternates between loud and soft as you rotate through the angles where the interference is constructive and destructive • Waves can interfere so destructively with one another that they produce dead spots, or places where no sound at all can be heard.
Sound Interference Engineers who design theaters or auditoriums must take into account sound wave interference. The shape of the building or stage and the materials used to build it are chosen based on interference patterns. They want every member of the audience to hear loud, clear sounds.
3D • 3D is becoming a huge part of our social technology. We have 3D movies, 3D glasses, and even 3D TVS. Have you ever asked yourself though, how 3D really works? • Three dimensional figures width, height, and depth. The most important things to make an image look 3D are shapes, surface textures, lighting, perspective, depth of field and anti-aliasing. • Light plays a huge roll in 3D and the creators must consider it. The differences in light intensity work with shape to reinforce the illusion that an object has depth as well as height and width. The illusion of weight comes from the second effect -- shadows.
Another optical technique used is depth of field. This gives the watcher an illusion of depth and that it is why the 3D pictures seem to “pop” out at you. • Another way that creators use to fool the eye is anti-aliasing. Pixels surrounding the object are different colors giving it more depth. • Through optical illusions and tricks creators can make on the screen they make the images they made pop out in 3D form.
This is what a 3D image looks like without 3D glasses. The glasses help make the image “pop” because the two main colors of the tiger are red and blue. The red and blue of the glasses lenses allow only one color to enter each eye. After that our brain does the rest and the object becomes 3 dimensional.