Explanation: In this video, it demonstrates a light trick, about how an object can “Vanish” in the oil. Which used a beaker filled with oil, then simply put in the other smaller beakers, also several stirring rods. At first, when he put the stirring rod into the water, we can clearly see that, but when he put the same stirring rod into the oil, the part of stirring rod in the oil “disappeared”. Then, he showed us, when he put the smaller beaker into the oil, same thing happened, we can barely see the beaker in the water. That’s becuase the index of refraction of oil and stirring rod and other beakers are very similar. Refraction occurs when a wave changes in the direction as it pass from one medium to another. The index of refraction describes how much the light will bend numerically, this number indicated the speed of light in the certain medium. When light passes from air into glass, it slows down. It changed the speed leads to the light reflect and refract. When the difference between the index of refraction of two different materials decreases, the less reflection and refraction while the light travel through two mediums. Therefore, it makes the transparent object looks like “invisible” in that medium.
Description: This video showed one of the wave interferences—Destructive. Which is one end flick the slinky down, and the other end will flick the slinky up at the same time. This experiment demonstrates when one crest met a trough, they will cancel each other out in the middle, and then keep moving to the end with the same amplitude.
Description: In constructive interference, when one crest met another crest (or one trough met another trough), the amplitude of crest would doubled, and then back to the original amplitude and move to the end of string.
Description: non-repeating wave; single disturbance.
Description: wave recurring at regular intervals. Requires regularly repeating disturbances.
Description: spring is pulled sideways (disturbance is at right angle to the direction that the wave will travel)
Description: several turns of the spring are compressed and let go; Disturbance is in the same direction as the direction of travel.