Purpose: When light travels through different mediums, it is being refracted. The purpose of this lab is to test Snell’s law of refraction. Hypothesis: The angles of refraction that I predicted from the angle of incidences by using Snell’s Law are below on the predicted angle Column. To obtain these values I used the index of refraction of crown glass because it is more likely close to the glass (plexiglass) that we are using. Angle of Incidence 0° 10° 20° 30° 40° 50° 60° Predicted angle of refraction 0 6.56° 13.0° 19.2° 25.02° 30.27° 34.74° Variables and Controls: Independent Variable: The angle of the light coming from the ray box or the angle of incidence Dependent Variable: The angle of refraction on the plexiglass.
Objective The purpose of this experiment is to prove the laws of reflection and refraction, and to determine the angle of the total internal reflection and the index of refraction in the experiment. Theory The theory being experimented in this procedure is that of Willebrord Snell. From his theory we understand that the incident ray, the normal line and the refracted ray all lie on the same plane. We also understand that the relationship is defined in a ratio with the following equation; Which means that the ratio of the sine of the angle of incidence to the sine of the angle of refraction, I equal to the ratio of the speed of light in the original medium and the speed of light in the refracting medium. Procedure We set up the optics track, light source and the ray table.
Use a protractor to measure the angle from the reference line to the lines drawn in step 6. 8. Record the angle created by the laser pointer through the air as the Angle of Instance and the angle created by the laser pointer through the water as the Angle of Refraction. 9. Use Snell's Law to determine the Index of Refraction of Water.
By measuring the angles of diffraction and by calculating the grating spacing, the wavelength of the light may be calculated. The light source used in the experiment should be a monochromatic light source as the experiment requires light of a single wavelength in order for the wavelength to be calculated. The second part of the experiment demonstrates how to determine the measurement of the groove spacing of a CD. The CD is used as a reflective grating; the light is reflected from the surface of the cd some of the reflected angles will give rise to constructive maxima, similar to a diffraction grating. The last part of the experiment is to determine the measurement of the diameter of powder spores by passing a monochromatic light source through a circular aperture and producing a diffraction pattern of concentric rings.
Dependent variable(s) Angle of refraction Measure the angle with a protractor. Controlled variable(s) The refractive index The position of the Perspex Trace it on a piece of paper, this is where it will be placed it it got moved. Same light source Same ray box Same protractor and unit Use the same protractor Same piece of Perspex Use only one Perspex prism Hypothesis: If a light is shone at the Perspex, then the light will be refracted because of the shape of the Perspex, and because it is pasting through a medium. If the angle of incidence and refraction was measured and calculated the refracted index would be about 1.49, since the refractive index of a substance is always the same. Equipment: - Ray box - Power supply - Wires - Perspex prism - Paper - Ruler and protractor - Single slit slide - Quadruplet slits slide - 2 colored slides Method: 1.
Snell's Law In the previous sections we studied light reflecting off various surfaces. What happens when light passes from one medium into another? The speed of light, like that of all waves, is dependent on the medium through which it is travelling. When light moves from one medium into another (for example, from air to glass), the speed of light changes. If the light ray hits the boundary of the new medium (for example the edge of a glass block) at any angle which is not perpendicular to or parallel with the boundary, the light ray will change its direction through the next medium, or appear to `bend'.
The attenuation of glass optical fiber is caused by two factors, absorption and scattering. Absorption occurs in several specific wavelengths called water bands due to the absorption by minute amounts of water vapor in the glass. Energy of this type of wave. 3. How is this type of wave created?
REFLECTION, REFRACTION, DIFFRACTION Reflection – waves bounce off a surface Refraction – waves bend when they pass though a boundary Diffraction – waves spread out (bend) when they pass through a small opening or move around a barrier REFLECTION - when a wave encounters a barrier, it can reflect the bounce off the obstacle - i.e. light = mirror; sound = echo - most objects we see reflect light rather than emit their own light - Fermat’s principle = light travels in straight lines and will take the path of least time Laws of Reflection 1. The angle of incidence equals the angle of reflection (true for both flat and curve mirrors) 2. The incidence ray, reflected ray, and the normal all lie in the same plane. Specular vs. Diffuse Reflection - in diffuse, waves are reflected in many different ways form a rough surface - in specular, waves are reflected in the same direction from a smooth surface REFRACTION (light) - when one medium ends and another begins, that is called boundary - when a wave encounters a boundary that is denser, part of it is reflected and a part of it is transmitted - the frequency of the wave is not altered when crossing the boundary / barrier but the speed and wavelength are - the change in speed and wavelength can cause the wave to bend if it hits the boundary at an angle other than 90 degrees - this bending as light enters the water can cause objects under water to appear at a different location than they actually are REFRACTION (sound) - sound waves bend when passing into cooler / warmer air because the speed of sound depends in the temperature of the air - sound travels slower in cooler air REFRACTION (water) - water waves bend when they pass from deep water into shallow water, the wavelength shortens and they slow down.
Fermat’s Principle of Least Time. Imagine that we want to analyze the trajectory of light reflecting off of a surface. Consider the following diagram below: Here the horizontal black line is the medium that the light is bouncing off of. The red line represents the path that the light would travel if it continued on unimpeded by the reflective medium. The blue line and the orange line are equal and so by basic geometry the reflected line and the red line are equal in length.
Edward Gray NT1310 07/29/2013 Assignment 7 Reflection, Refraction and Degradation. The law of reflection states that if light hits a reflective surface at a certain angle, (angle of incidence), it will reflect or bounce off at the same angle, (angle of reflection.) A Mirror is a good example of reflection. Mirrors have smooth shiny surfaces that absorb very little light, so they reflect light in almost exactly the same pattern as it hits, which allows us to see a complete reflected image of objects. Mirrors can reflect images of objects because light rays bounce off an object, travel in a straight line to a mirror, bounce off the mirror, and then travel to the eye of an observer.