Chapter 26

IWP Applets for Chapter 26

ID/Type	Web Link or WA Question Code	Local download	Launch from browser	Description
L17	Refraction	refraction-in-box-2.iwp	refraction-in-box-2.iwp	A ray of light (red) is incident from air on a transparent medium (blue box). The ray enters from the bottom of the screen. The initial angle of incidence is the smallest that it can be in order to result in a refracted ray emerging from the right side of the box. At smaller angles, the ray would be totally reflected internally from the right boundary of the box. The animation can be played in order to increase the angle of incidence.
P22	Ray Tracing and Image Formation in Plane Mirrors	mirror-plane-ray-tracing-01.iwp	mirror-plane-ray-tracing-01.iwp	Step through the applet to see light rays traced to locate the position of the image. Two rays each are traced from the head and tail of the object arrow to the mirror. The rays reflect to the observer according to the law of reflection. Virtual rays are shown as gray lines to the right of (behind) the mirror. After the image is drawn, change the X- or Y-coordinate of the head or tail to see the construction instantly redraw. Click Reset to redraw the construction step-by-step. Unphysical results are obtained for positive X-coordinates of the object.
P22	Ray Tracing and Image Formation in Plane Mirrors	mirror-plane-ray-tracing.iwp	mirror-plane-ray-tracing.iwp	Step through the applet to see light rays traced to locate the position of the image. Two rays each are traced from the head and tail of the object arrow to the mirror. The rays reflect according to the law of reflection. Virtual rays are shown as gray lines to the right of (behind) the mirror. After the image is drawn, change the X- or Y-coordinate of the head or tail to see the construction instantly redraw. Click Reset to redraw the construction step-by-step. Unphysical results are obtained for positive X-coordinates of the object.
P23	Ray Tracing and Image Formation for Spherical Mirrors	mirror-concave-ray-tracing-01.iwp	mirror-concave-ray-tracing-01.iwp	An object arrow is shown to the left of a concave mirror and outside of the focal point. (The mirror is represented by a straight black line for simplicity.) Step through the applet frame-by-frame to see the principal rays and image drawn sequentially. (red = C ray, purple = P ray; green = F ray) While it appears that the rays do not obey the law of reflection at the mirror, this is simply due to the fact that the mirror is drawn as a straight line rather than a curve. This applet will only construct real images. If the object is placed inside the focal point, the applet will not draw. Negative values for the focal length or object distance may produce incorrect results. To see a grid, enter 0 for Background.
P23	Ray Tracing and Image Formation for Spherical Mirrors	mirror-concave-ray-tracing-02.iwp	mirror-concave-ray-tracing-02.iwp	An object arrow is shown to the left of a concave mirror and inside the focal point. (The mirror is represented by a straight black line for simplicity.) Step through the applet frame-by-frame to see the principal rays and image drawn sequentially. (red = C ray, purple = P ray, green = F ray) Apparent rays (shown dashed in the text) are turquoise. While it appears that the rays do not obey the law of reflection at the mirror, this is simply due to the fact that the mirror is drawn as a straight line rather than a curve. The applet will only construct virtual images. If the object is placed outside the focal point, the applet will not draw. Negative values for the focal length or object distance may produce incorrect results. In order to see a grid, enter 0 for Background.
P23	Ray Tracing and Image Formation for Spherical Mirrors	mirror-convex-ray-tracing-03.iwp	mirror-convex-ray-tracing-03.iwp	An object arrow is shown to the left of a convex mirror. (The mirror is represented by a straight black line for simplicity.) Step through the applet frame-by-frame to see the principal rays and image drawn sequentially. (red = C ray, purple = P ray, green = F ray) Apparent rays (shown dashed in the text) are turquoise. While it appears that the rays do not obey the law of reflection at the mirror, this is simply due to the fact that the mirror is drawn as a straight line rather than a curve. Positive values for the focal length or negative values for the object distance may produce incorrect results. In order to see a grid, enter 0 for Background.
P24	Refraction of Waves	refracted-waves-5.iwp	refracted-waves-5.iwp	Plane waves of constant frequency move up the screen, crossing from one medium into another. The wave speed decreases in the upper medium. Since the frequency is constant and speed = frequency x wavelength, the wavelength is less in the upper medium. The arrows indicate the incident and refracted rays. The rays are perpendicular to the wavefronts. The red tic marks on the left side of the Animator window are spaced 2.0 cm apart.
P24A	APB-P24-01t	refracted-waves-5.iwp	refracted-waves-5.iwp	Plane waves of constant frequency move up the screen, crossing from one medium into another. The wave speed decreases in the upper medium. Since the frequency is constant and speed = frequency x wavelength, the wavelength is less in the upper medium. The arrows indicate the incident and refracted rays. The rays are perpendicular to the wavefronts. The red tic marks on the left side of the Animator window are spaced 2.0 cm apart.
P24A	APB-P24-02t	refracted-waves-6b.iwp	refracted-waves-6b.iwp	Plane waves cross a boundary between two media at a non-zero angle of incidence. The angles of incidence and refraction are shown with respect to the normal to the boundary.
P25	Ray Tracing and Image Formation by Lenses	lens-ray-tracing-01.iwp	lens-ray-tracing-01.iwp	An object arrow is shown to the left of a converging lens and outside a focal point. (The lens is represented by a straight black line for simplicity.) Step through the applet frame-by-frame to see the principal rays and image drawn sequentially. (red = C ray; purple = P ray; green = F ray) This applet will only construct real images. If the object is placed inside the focal point, the applet will not draw. Negative values for the focal length or object distance may produce incorrect results.
P25	Ray Tracing and Image Formation by Lenses	lens-ray-tracing-02.iwp	lens-ray-tracing-02.iwp	An object arrow is shown to the left of a converging lens and inside the focal point. (The lens is represented by a straight blue line for simplicity.) Step through the applet frame-by-frame to see the principal rays (red = C ray; purple = P ray; green = F ray) drawn sequentially. The rays that refract through the lens are extended backward (light gray lines) in order to locate the position of the head of the image. In order to remove the background to expose a grid, enter 0 for the Background input. This applet will only construct virtual images. If the object is placed outside the focal point, the applet will not draw. Negative values for the focal length or object distance may produce incorrect results.
P25	Ray Tracing and Image Formation by Lenses	lens-ray-tracing-03.iwp	lens-ray-tracing-03.iwp	An object arrow is shown to the left of a diverging lens. (The lens is represented by a straight black line for simplicity.) Step through the applet frame-by-frame to see the principal rays (red = C ray; purple = P ray; green = F ray) drawn sequentially. The rays that refract through the lens are extended backward (light gray lines) in order to locate the position of the head of the image. In order to remove the background to expose a grid, enter 0 for the Background input. Negative values for the object distance may produce incorrect results.
M13	Problems on Refraction	ray-refraction-3d.iwp	ray-refraction-3d.iwp	The red line at y = 0 represents a boundary between media of different indices of refraction. The path of a light ray is shown in blue. Playing the applet forward or backwards will increase or decrease the angle of incidence. Take measurements from the applet to determine the ratio of the index of refraction of the upper medium to that of the lower medium. You can determine angles of incidence and refraction by finding ratios of the legs of right triangles. In order to improve the accuracy of your measurements, run the applet to obtain the largest angles possible.
M13	Problems on Refraction	ray-refraction-3b.iwp	ray-refraction-3b.iwp	The blue and gray areas represent media of different indices of refraction. n2/n1 is the ratio of the index of refraction of the gray medium to that of the blue medium. The normal to the boundary is shown in red. The path of a light ray is shown in yellow. The ray is incident from the blue medium. Both a refracted and reflected ray are produced at the boundary. Playing the applet forward or backwards will increase or decrease the angle of incidence. Explain why the refracted ray disappears at a particular angle. Use Snell's Law to show that the angle at which the refracted ray disappears is correct. Values of the angles of incidence and refraction are given as outputs.
M13	Problems on Refraction	ray-refraction-4c.iwp	ray-refraction-4c.iwp	The blue, red, and gray areas represent media of different indices of refraction. (The media are indexed 1,2,3 from the bottom up.) The path of a light ray is shown in yellow. The ray is incident from the blue medium. Playing the applet forward or backwards will increase or decrease the initial angle of incidence. The indices of refraction of the blue and gray media are given. The angle of incidence in the blue medium is given as an output. Determine the corresponding angle of refraction in the gray medium. (Why isn't it necessary to know the index of refraction or angle of refraction in the red medium?)
M13	Problems on Refraction	ray-refraction-4e.iwp	ray-refraction-4e.iwp	The blue, red, and gray areas represent media of different indices of refraction. 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.
M13ext	APB-M13-01b	ray-refraction-3g.iwp	ray-refraction-3g.iwp	The red line at y = 0 represents a boundary between media of different indices of refraction. The path of a light ray is shown in blue. Note that both a reflected and a refracted ray are produced at the boundary. This problem is concerned with the refracted ray. Playing the applet forward or backwards will increase or decrease the angle of incidence. Take measurements from the applet to determine the ratio of the index of refraction of the upper medium to that of the lower medium. You can determine angles of incidence and refraction by finding ratios of the legs of right triangles. In order to improve the accuracy of your measurements, run the applet to obtain the largest angles possible.
M13ext	APB-M13-02b	ray-refraction-3h.iwp	ray-refraction-3h.iwp	A ray of light starting from lower left is refracted from Medium 1 to Medium 2 as well as reflected into Medium 1. Playing the applet forward or backwards will increase or decrease the angle of incidence. The normal to the boundary is shown in red. Which medium has the greater index of refraction? How do you know? If n2/n1 is the ratio of the corresponding indices of refraction of the two media, determine the value of n2/n1.
M13ext	APB-M13-03b	ray-refraction-3i.iwp	ray-refraction-3i.iwp	A ray of light travels through 3 successive media from 1 to 3.. The indices of refraction of media 1 and 3 are given as inputs. Normals are shown at the boundaries of adjacent media. The angle of incidence in Medium 1 and the angle of refraction into Medium 3 are marked. Which medium has the greatest index of refraction? How do you know? Determine the angle of refraction in Medium 3. (Why isn't it necessary to know the index of refraction or angle of refraction in Medium 2?)
M13ext	APB-M13-04b	ray-refraction-4e.iwp	ray-refraction-4e.iwp	The blue, red, and gray areas represent media of different indices of refraction. 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.
M13ext	APB-26-03-01b	prism-1b.iwp	prism-1b.iwp	A ray of light is incident from air on a prism with index of refraction 1.5. Playing the animation will increase the angle of incidence in 1 degree increments. Normals to the sides of the prism are indicated by red lines. The angle of incidence i is given as an output. The vertex angle v can be adjusted. For a particular angle of incidence, use Snell's Law and the geometry of the prism to determine the angle of refraction at which the ray emerges from the prism on the right.
M13ext	APB-26-03-03b	prism-6b.iwp	prism-6b.iwp	The dispersion of white light by an equilateral prism made of crown glass is modeled. The index of refraction ranges from 1.513 for red light to 1.532 for violet light. Playing the animation will decrease the angle of incidence in 1 degree increments. (The colored rays emerging from the prism represent broader bands of color that would appear in an actual situation. That is, the spread of colors from red to blue would be along a continuum rather in discrete lines.) For any particular angle of incidence, determine the angular spread between the emerging red and violet rays, assuming the indices of refraction given above
M13ext	APB-26-03-04b	rainbow-01.iwp	rainbow-01.iwp	A rainbow is formed when the direction of sunlight to raindrops is such that a ray internally reflected in a drop refracts out of the drop along a line of sight that reaches the observer. The angular difference between the direction of the sunlight and the direction of the refracted ray to the observer depends on the frequency of the light, since the speed of light in water depends on frequency. This is why a spectrum of colors is produced in the rainbow. The raindrop acts like a prism. The index of refraction of 1.331 is for red light. Run the applet to see how the Angular Difference increases as the index of refraction is increased in increments of 0.001 to the value of 1.343 for violet light at the opposite end of the visible light spectrum. The black lines are normals to the raindrop.