Physics+Animations

= [|Waves: Constructive and Destructive Interference] = This animation shows and explains the constructive and destructive interference of two waves. The two waves, one red and one yellow, run over each other repeatedly. As the crests of two waves meet, the amplitude is doubled, showing a large resultant crest. As the crest of the red wave meets the trough of the yellow wave, they cancel out, leaving no waves at all. Then finally, as the troughs of both waves meet, the amplitude doubles and a large resultant trough appears.

To see this animation, you don't have to do anything. Just click on the link. Once the video is done loading, it will start by itself and repeat over and over again. = = = [|Refraction: Internal Reflection] = This animation demonstrates the reflection of light in a block as it approaches and passes the point of internal reflection. The light source starts out pointing vertically, and is then lowered into the block. The light passes through the block until it reaches its **critical angle** (when the angle of refraction is 90 degrees and the light ray reflects across the block's surface). After it passes this point, the light has reached internal reflection, where it does not leave the block, but reflects off of its surfaces. This animation helped me fully understand what the **critical angle** and **internal reflection** are.

To see this animation, once again, just click on the link. The video will begin and repeat itself on a loop on its own.

= [|Sound Waves: Beats] = This animation explains the phenomenon of beats, which are made by two conflicting sound waves at slightly different frequencies. The demonstration has several slides, which effectively explain sound beats. The first scene is simply a basic description of beats, with an animation of two pitch forks with close, but differing frequencies. The second slide is a demonstration of two drums playing slightly different beats. Every so often the drums are synchronized, representing the behavior of beats of sound waves. The third slide is another representation of two sound waves, using oscillators at different frequencies. Just like on slide 2, the oscillators are synchronized every so often. The fourth and fifth slides, 'visualize the sum' of two waves, by displaying two waves and their resultant. It then goes on to show the mathematics of sound beats. Finally, on slide 6, there is an auditory demonstration of sound beats. This part is pretty cool. We get to hear what 2 almost-identical pitch frequencies separately, and then what they sound like together. The result is pretty amazing, proving what sound beats really sound like.

To use this animation, go through each slide. When you're done with one, click the button that says 'next scene'. Once you reach the final slide, click on each button separately to hear each demonstration. Click the 'stop' button to end the sound.