Browsing Animations: Optics

4 Animations



This applet draws wavefront diagrams of waves from two sources.



Two sources of monochromatic waves are situated on either side of the origin. The sources oscillate in phase. The pattern of interference fringes is projected on a screen near the top of the display. Playing the animation will decrease the source separation and show the resulting change in the interference pattern. Actual fringes would have intensity variations that can't be displayed in the animation.



The blue, red, and gray areas represent media of different indices of refraction. They are indexed 1 to 3 from the bottom up. The path of a light ray incident from the blue medium is shown in yellow. The angle of incidence is given as an output. Playing the applet forward or reverse will increase or decrease the initial angle of incidence. In order to increase the precision with which the incident angle can be read, decrease the Angle Increment. Also change the Starting angle to something very near the angle you're looking for so that you don't have to step through many angles. The problem is to find the relative indices of refraction n1:n2:n3. That is, find the ratios n2/n1 and n3/n2. For good results, measure angles to the nearest tenth of a degree.



Plane waves of constant frequency move up the screen, crossing from one medium (blue) into another (gray). The wave speed in each medium is different.