Extra Resources: Unit 3
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Wave Interference
This simulation demonstrates how waves in water, sound, and light have similar wave properties. Constructive and destructive interference can be demonstrated using a double slit to create a diffraction pattern. Go to the download page for more information or click on the image on the right to download the simulation. |
Reference Frames
Movement is not observed relative to some universal, stationary frame. Rather, we can only observe motion by comparing to the position of other objects. A reference frame relates objects to each other by how they are moving. For example, when you are in a car, driving down the road, you see other passengers at rest in your reference frame, while you see the road moving past. If you are standing next to the road, you see the road as stationary in your reference frame while the car appears to be moving.
Imagine you are in a truck, driving at the speed of a cannonball, and you shoot a cannonball behind you. You will see it move away from you quickly, going away behind the truck at the same speed as the road. This means that someone standing next to the road will see the truck go past, while the cannonball is stationary, or as seen in the image below, fall straight down.
Movement is not observed relative to some universal, stationary frame. Rather, we can only observe motion by comparing to the position of other objects. A reference frame relates objects to each other by how they are moving. For example, when you are in a car, driving down the road, you see other passengers at rest in your reference frame, while you see the road moving past. If you are standing next to the road, you see the road as stationary in your reference frame while the car appears to be moving.
Imagine you are in a truck, driving at the speed of a cannonball, and you shoot a cannonball behind you. You will see it move away from you quickly, going away behind the truck at the same speed as the road. This means that someone standing next to the road will see the truck go past, while the cannonball is stationary, or as seen in the image below, fall straight down.
The image above is from an episode of Mythbusters where they show that this effect where the ball shot backwards from a moving vehicle will fall straight down. This video shows more.
Time Dilation
This video by Adam Magyar showing the slow motion view from a train pulling into a station can be used to illustrate the time dilation of objects moving at extremely high speeds. As the train station appears to move to the left, a person on the train will see the people in the station appear to move slower through time. However, in the reference frame of the train station, it appears that the train is moving. This means that to a person standing still in the station, it will appear that the people on the train move slower through time with the same time dilation.
This video by Adam Magyar showing the slow motion view from a train pulling into a station can be used to illustrate the time dilation of objects moving at extremely high speeds. As the train station appears to move to the left, a person on the train will see the people in the station appear to move slower through time. However, in the reference frame of the train station, it appears that the train is moving. This means that to a person standing still in the station, it will appear that the people on the train move slower through time with the same time dilation.
Stainless, Alexanderplatz from Adam Magyar on Vimeo.
Blackbody Radiation
This interactive demonstrates how the blackbody spectrum of a star changes with temperature. Click on the image to use. This interactive was created by McGraw-Hill, with more simulations found here. |
The electromagnetic radiation that's emitted from an object depends on its temperature. Colder objects give off infrared radiation. As an object is heated, it starts to give off visible light that we can see as shown in the image below. First it gives off red light, then more yellow, and then it emits all the colors and looks white hot. Stars are so hot they give off ultraviolet radiation and can look blue.
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Electrons through a Double Slit
The images below show the difference between the pattern electrons would be expected to make when they pass through a double slit if they are particles (left) or waves (right). Electrons make the pattern on the right, showing their wave-particle duality nature.
The images below show the difference between the pattern electrons would be expected to make when they pass through a double slit if they are particles (left) or waves (right). Electrons make the pattern on the right, showing their wave-particle duality nature.
These simulations were created by teachers for the PhET Interactive Simulations Project at the University of Colorado at Boulder. Visit their site to see more simulations on Quantum Phenomena.
The Photoelectric Effect
This applet demonstrates how the kinetic energy of electrons that are released due to photoionization depends on the frequency of the ionizing light, not the amplitude. This photoelectric effect is due to the particle nature of light, being made up of quantized packets of energy called photons. Go to the download page for more information or click on the image on the right to download the simulation. |