Tell us what’s wrong with it:
Thanks, got it!
We will moderate it soon!
Name: Melvin Dudley Date: 04-25-2022 Student Exploration: Laser Reflection Directions: Follow the instructions to go through the simulation. Respond to the questions andprompts in the orange boxes. Vocabulary: angle of incidence, angle of reflection, laser, law of reflection, plane mirror, reflection Prior Knowledge Questions (Do these BEFORE using the Gizmo.) Imagine you shine a flashlight directly at a mirror, as shown below. 1. Click the image, click Edit ✏ Draw an arrow showing the direction you thinkthe beam of light will most likely reflectoff the mirror. 2. Click the image, click Edit ✏ Suppose you tilt the mirror. Draw an arrowshowing the direction the beam will mostlikely reflect off the mirror now. Gizmo Warm-up Flashlights produce wide beams of light that havevarious wavelengths. A laser , on the other hand, is a narrow beam of light with only one wavelength. All thewaves in a laser beam are parallel to one another. As aresult, lasers are ideal for studying reflection , or how waves bounce off a surface. Using the Laser Reflection Gizmo, you can adjust the position of a laser beam and mirror to study how lightbehaves when it is reflected. 1. Drag the Angle slider back and forth. Describe what happens to the reflected laser beam: The laser beam reflects at a varied angle depending on how far the angle slider is adjustedback and forth. The laser beam is reflected at a negative angle when the angle slider ismoved to the left, and at a positive angle when the slider is pushed to the right. 2. Drag the laser up and down. Describe what happens to the reflected laser beam: The laser's reflection point moves when the laser is moved up and down. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
Activity A: Reflection from aplane mirror Get the Gizmo ready: ● Set the Laser location to 0 cm. ● Set the Angle to 25 degrees. ● Make sure Plane mirror is selected. Introduction: A plane mirror is a perfectly flat, smooth surface. In this activity, you will study how plane mirrors reflect light. Question: How does the angle of a mirror determine the angle of the reflected light? 1. Observe: Turn on Show normal . The normal is the dotted line perpendicular to the mirror. The angle of incidence ( θ i ) is the angle between the incoming laser beam and the normal. The angle of reflection ( θ r ) is the angle between the reflected laser beam and the normal. Move the Angle slider back and forth. What do you notice about the sizes of θ i and θ r ? When the angle slider is moved back and forth the sizes of grow and shrink, but they arealways the same size as each other. 2. Measure: Set the Angle to 40 degrees and turn on Show protractor . Each marking on the protractor represents 10 degrees. What do θ i and θ r equal? θ i = θ r = 3. Make a rule: What is the relationship between θ i and θ r ? Turn on Show angles and move the Angle slider back and forth. Was your rule correct? My rule was accurate, therefore yes. The law of reflection states that the angle of incidence is equal to the angle of reflection. 4. Gather data: Use the Gizmo to complete the table below. Mirror angle Angle of incidence ( θ i ) Angle of reflection ( θ r ) 0° Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
25° 50° 5. Make a rule: How is the mirror angle related to the angles of incidence and reflection? The angles of incidence and reflection coincide with the mirror angle. Activity B: Reflection fromnon-planarmirrors Get the Gizmo ready: ● Turn off Show normal and Show protractor . ● Set the mirror Angle to 50°. Question: How can you use the angle of refraction to determine the shape of a non-planarmirror’s surface? 1. Observe: Turn on Insert beam splitter . How do the seven incoming beams compare with one another? How do the reflected beams compare with one another? All seven of the incoming beams are equally spaced apart, as are all seven of the reflected rays. 2. Observe: From the dropdown menu at lower right, select Mirror 1 . Unlike the plane mirror, mirror 1 is not flat. A. Describe how the laser beams changed: The distance between the lasers has changed, as have the angles at whichthey reflect. B. Why do you think this happened? This occurred as a result of the mirror'suneven surface. 3. Solve: Turn off Insert beam splitter . Set the mirror’s Angle to 0 degrees and the Laser location to 35 cm. Check that Show angles is on. A. What are the angle of incidence and angle of reflection ( θ i and θ r )? The angle of incidence and angle of reflection are both B. What does this tell you about the surface of the mirror in this location? This indicates that the mirror's surface is inclined downward where it is. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
C. Move the Laser location to 14 cm. How did the orientation of the beam change? Now the beam has been upwardly reflected. D. What does this tell you about the surface of the mirror in this location? This indicates that the mirror's surface is tilted up in this area. 4. Summarize: What does it mean if the reflected beam is above the incident beam? What does it mean if the reflected beam is below the incident beam? If the reflected beam is higher than the incident beam, it is reflecting off of an upwardly slopedsurface, and if it is lower than the incident beam, it is reflecting off of a downwardly angledsurface. 5. Collect data: You will now use the laser to map the surfaces of mirrors 1, 2, and 3. In the rows of thetable, record each mirror’s angle at all the listedlocations. If the beam is deflected downward, theangle is negative. Otherwise the angle is positive. Height Mirror 1 Angle Mirror 2 Angle Mirror 3 Angle 35 cm -3.5 3.8 0 30 cm -5 2.5 5 25 cm -3.5 1.3 0 20 cm 0 0 -5 15 cm 3.5 -1.3 0 10 cm 5 -2.5 5 5 cm 3.5 -3.8 0 0 cm 0 -5 -5 -5 cm -3.5 -3.8 0 -10 cm -5 -2.5 5 -15 cm -3.5 -1.3 0 -20 cm 0 0 -5 -25 cm -3.5 -1.3 0 -30 cm -5 -2.5 5 -35 cm -3.5 -3.8 0 Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
6. Draw: Click the image, click Edit ✏ Use the data you collected to create drawings of themirrors’ surfaces in the boxes below. Be sureto pay attention to negative signs, whichindicate the direction of the angle. Mirror 1 Mirror 2 Mirror 3 7. Analyze: Does the law of reflection hold true for mirrors that aren’t flat? Use the Gizmo to explore this question, and describe your findings. Yes, non-flat mirrors are still subject to the law of reflection. Even if the mirror is curved, thepoint at which the laser hits it and reflects off of it is flat because the laser hits the mirror atsuch a small spot. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
Please login or register to post comments
Laser Reflection Gizmo Answer Key