Search the Community
Showing results for tags 'reflection'.
Found 5 results
Relahi posted a blog entry in physics blogI'm sure we all remember the poplular Youtube hit where the hiker becomes completely overwhelmed with emotion at the sight of a "double rainbow all the way across the sky." So, maybe his reaction was slightly over dramatic, but the science behind the phenomenon is pretty exciting. Try to contain yourselves though. In order for a rainbow to form, there are a couplel conditions: there must be a lot of moisture in the air and the sun must be behind us. Sunlight is white and is made up of the combination of frequencies from the colors in the visible light spectrum . When the sunlight hits the droplets of water, they act as miniature prisms. The white light is refracted into the drop at the boundary between air and water. The difference in mediums and and the increase in the index of refraction causes the light to slow down and change direction. Then it is reflected off of the inside of the back of the drop and refracted once again as it exits the drop, this time being dispersed into the white light's components on the visible light spectrum: red, orange, yellow, green, blue and violet. The angle of reflection inside the drop is between 40 and 42 degrees. Although each individual drop disperses the entire visible light spectrum, the rainbow appears to be split into separate bands of color. This is because our eye percieves the drops that lie at a steeper angle to be red and the drops that lie at a less steep angle to be violet. Therefore, a rainbow appears differntly to different observers depending on their location. When the sun reaches an angle above 42 degrees in the sky, the rainbow will dissapear. A rainbow is not a fixed point or a tangible object, it is only the way our eye percieves refracted light at 40- 42 degrees. So what about the legendary double rainbow? A double rainbow is formed when the sunlight is reflected at two points on the inside of the raindrop instead of just one. This second reflection creates a secondary rainbow at an angle of 50-53 degrees, making it appear higher in the sky. The colors are in reverse order because the light is bent again as it leaves the raindrop. Circular rainbow?? Yes, rainbows are actually circular. From the ground we only see the top half of the circle because of the presence of the ground. If you were to see a rainbow from an airplane you may see the entire circle.
The Workings of Reflecting Telescopes
running_dry posted a blog entry in Tired and a little dehydratedThe second major type of telescope is the reflecting telescope. The reflecting telescope was invented by Newton and considered an improvement on Galileo's design. Most reflecting scopes still use Newton's design. Reflecting scopes use a wide concave mirror at the back of the tube to bring light to a focal point in front of the mirror which is then usually reflected sideways toward the eyepiece by a flat, angled mirror. There are also compound scopes that work like reflecting scopes but there is a hole in the center of the concave mirror and the mirror at the foal point reflects light back through the hole where it is magnified by an eyepiece at the end of the tube. Below are diagrams of both reflecting and compound telescopes. Now for some pros and cons. Refractor tubes are usually longer and skinnier, thus have smaller apertures (and cost more per unit of aperture length); while reflectors are wider and shorter with larger apertures (and less cost per unit of aperture length). Because of this, refractors are usually more expensive and better for observing close planets while reflectors are better for observing deep sky objects like galaxies and nebulae.
Fun in Physics Class
kphysics15 posted a blog entry in kphysics15During my first week of physics class i felt completely lost! I wanted to understand physics so badly! I love math; so I was confused as to why I was not understanding physics. We were learning kinematics and I had no idea what was happening. What's velocity? What's acceleration? These were some of the questions I was asking myself. After much practice I finally got the hang of it! Looking back at kinematics it seems so easy! Hopefully with some of the harder material I will feel the same way! One of my favorite experiments we did in class was watching what happens with an electroscope. An electroscope is a model that demonstrates the movement of electric charge. Check out the video I posted below to learn all about an electroscope!
The Physics of Drawing- Light Waves and Colors
hollyferg posted a blog entry in hollyferg's BlogDrawing is much more complicated than many people think. It also has a lot to do with physics. The main physics behind drawing is light waves. This is because light is a type of wave, which carries energy like all other waves. Light is essential for drawing, or any other kind of art. Light allows you to see, and more specifically, it allows you to see an object’s shape, color and the shadows on it. Being able to see all these things makes it possible to take a 3D object and put it on a piece of paper. The way light lets you to see objects and colors is by reflection. White light is where all the colors in the spectrum of visible light appear all at once. Examples of this is the sun. These pictures show each color's wavelength. Red has a long wavelength, violet has a small shorter one. All of them together are white light. Different objects reflect a specific color, or type of light because of their different wavelengths. Space is the only true black because it absorbs all light and colors because there is nothing for light to reflect off of. An example of light reflection creating colors is an apple. When you look at it, you see it as the color red. This is because red light is reflected off of the apple and into receptors in your eye, and all the other colors are absorbed into the apple. So, when you are trying to draw or paint, or whatever else, you have to look at an object and observe its light. This object reflects light and creates color. But there are also shadows. Rounded objects allow light to diffract. Light waves want to travel in straight lines, but when they run into an object, they diffract, or bend slightly around the edge. This makes your eye see the object get gradually darker until there is barely any light reaching it, on the side facing away from the light waves. This is why it’s difficult to accurately draw things unless you know how to look at the light instead of just the object itself. Looking for the light and dark spots of the object is what makes it look 3D on paper. I have always wondered why it seems so hard to draw, but now I know its because I’ve just been looking at the shapes instead of paying more attention to the light on it. I’ll have to keep that in mind.
WS: Regents Law of Reflection
FizziksGuy posted a file in Waves