Lab Ripple Tank Student Involvement Sheet
Name __________________________________________  Period ____  Date _____________

A point source creates _______________  wavefronts. As a point source vibrates more quickly in the same medium, the frequency of the waves produced _______________  while their wavelength _______________  since the wave speed remains constant.

Remember that the _______________  governs a wave's frequency while the _______________  governs a wave's speed.

checklist  1. When a plane wave is reflected of a barrier, the angle of _______________  equals the angle of _______________. These angles are measured between a _______________  drawn to the interface or reflecting barrier and _______________  drawn perpendicular to the incident and reflected wavefronts.

NEATLY complete this sketch showing plane waves reflecting off an angled barrier. For the incident ray shown, construct the reflected ray and six reflected wavefronts. Label the angle of incidence and the angle of reflection. (Sample Solution)

checklist  2. When a plane wave is reflected by a parabolic barrier, the reflected wave is ________________________  in shape and has an apparent point source located at the _______________  of the parabola. Conversely, when a ___________________  wave is generated at the ___________________  of the parabola, its reflection is a plane wave.

On the next page, NEATLY complete this sketch showing plane waves reflecting off a parabolic barrier. For the two incident rays shown, construct the reflected rays and three circular reflections. (Sample Solution)

checklist  3. Complete the following sketch showing circular waves reflecting off of a plane barrier by constructing two reflected wavefronts. (Sample Solution)

NEATLY construct two normals, two reflected rays, the image source, and two reflected wavefronts. Use three colors:

#1:  initial wavefronts and incident rays
#2:  interface and normals
#3:  reflected rays and reflected wavefronts

checklist  4. When two point sources generate waves in the same medium simultaneously, they form an interference pattern. The region of constructive interference is called a(n) _____________, while the region of destructive interference is called a(n) ____________.

When two in-phase point sources of the same frequency move closer together, the amount of interference (increases, decreases, remains the same) as shown by the (increased, decreased, same) number of interference fringes. When the point sources move farther apart, the amount of interference (increases, decreases, remains the same) as shown by the (increased, decreased, same) number of interference fringes.

When two in-phase point sources of the same frequency remain a fixed distance apart and the frequency of the waves they produce is increased, the amount of interference (increases, decreases, remains the same) as shown by the (increased, decreased, same) number of interference fringes.

NEATLY complete the following sketch of a two in-phase source interference pattern. (Sample Solution)

Use three colors.

#1: Alternate the colors of the wavefronts, starting with the same initial color
#2: Draw in the resulting interference nodes (dotted lines) in the third color.
#3: Label the central maximum, CM, and the first 4 fringes: N1, A1, N2, A2, N3.

checklist  5. Diffraction occurs when waves bend ______________________________  or through an opening. The amount of diffraction, or curvature, increases as the width of the opening approaches the size of one _______________.

On the next page, NEATLY complete the following sketches contrasting the diffraction patterns through a narrow and a wide opening. (Sample Solution)

checklist  6. Refraction occurs when waves bend as a result of a ________________________  caused by a change in medium. In a fast medium, the wavelength is (longer, shorter) allowing a greater distance to be travelled each second; while in a slow medium, the wavelength is (longer, shorter) thereby restricting the distance travelled each second. The waves always bend (away from, towards) the normal when they enter a slower medium. The wave's _______________  remains constant, regardless of which medium through which the wave is traveling.

NEATLY sketch this phenomena in the space provided below. (Sample Solution)

Use three colors:

#1:  initial wavefronts, incident ray, incident angle
#2:  interface and normal
#3:  refracted wavefronts, refracted ray, refracted angle