1. Observe Observe your image on each side of a spoon. Record your observations using words and a picture.

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Stephen Carroll
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1 Concave Mirrors 1. Observe Observe your image on each side o a spoon. Record your observations using words and a picture. Inner spoon Outer spoon 2. Observe and Explain Observe the videos o the parallel light beams relecte o the concave mirror. Explain why the light beams are relected this way using the law o relection and normal lines or curves. Draw a diagram that represents what happens when beams o parallel light strike the concave mirror. The special point that they all converge to is called or the ocal point o the mirror.

2 3. Four Special Rays There are our rays that are easy to draw or concave mirrors. Draw each below: 1) An incident ray that is parallel to the optical axis: 2) An incident ray that travels through the ocal point o the mirror: 3) An incident ray that strikes the mirror at the optical axis: 4) An incident ray that strikes the center o the mirror: 4. Try it yoursel You place an object 3 meters in ront o a concave mirror that has a ocal point 1 meter rom the surace o the mirror. a) Draw a ray diagram or the situation: b) What will the object s image look like will it be (magniier reduced?) (real or virtual?) (upright or inverted?)

3 5. Try it yoursel The object is now placed 0.5 meters in ront o a concave mirror that has a ocal point 1 meter away rom the surace o the mirror. a) Draw a ray diagram or the situation b) What will the object s image look like will it be (magniier reduced?) (real or virtual?) (upright or inverted?) 6. Design an Experiment Design an experiment to experimentally locate the ocal length o a mirror. Write or draw your set up below. 7. Derive The ray diagram and the reasoning that ollows allows you to derive a mathematical relationship between the distance o the object rom a mirror, the distance o the image rom the mirror d i, and the ocal length o the mirror. Careully examine the derivation and evaluate the outcome using limiting case analysis and your knowledge o how lenses orm images o objects. AB is a bright object; A 1 B 1 is the image o the object. (M, N, and C are points on the mirror, where rays hit it.) B A O B 1 F M A 1 C N d i AM BC = (the rays are close to the main axis o the mirror). A 1 N B 1 C = d i ; CM BA, and CN B 1 A 1. ABF and CNF are similar triangles. Thus BF/CF = AB/A 1 B 1 or ( -)/ = AB/ A 1 B 1. A 1 B 1 F and MCF are similar triangles. Thus CF/B 1 F = CM/A 1 B 1 = AB/A 1 B 1 = /(d i ).

4 From this, we ind - = d i - or, ater some algebra, we get a relationship that is called the mirror equation: d i = 1. (a) Does the relationship make sense when the object is ininitely ar away? Support your answer with a ray diagram. (b) Does the relationship make sense i an object is placed right at the ocal point? Support your answer with a ray diagram. (c) Does the relationship make sense when the object is between the mirror and the ocal point? Support your answer with a ray diagram. (d) Describe careully all the assumptions that we made deriving the relationship.

5 Homework 8. Regular problem Use ray diagrams and the mirror equation derived in class to locate the position, orientation, and type o image ormed by an upright object held in ront o a concave mirror o ocal length +20 cm. The object distances are (a) 200 cm, (b) 40 cm, and (c) 10 cm. 9. Regular problem A large concave mirror o ocal length +3.0 m stands 20 m in ront o you. Describe the changing appearance o your image as you move rom 20 m to 1 m rom the mirror. Indicate distances rom the mirror where the change in appearance is dramatic. 10. Regular Problem Location the position, orientation, and type o image ormed by an upright object held in ront o a concave mirror o ocal length + 50 cm. The object distance is 100 cm. Include a ray diagram. 11. Regular Problem Locate the position, orientation, and type o image ormed by an upright object held in ront o a concave mirror o ocal length +50 cm. The object distance is +25 cm. Include a ray diagram. 12. Regular Problem Locate the position, orientation, and type o image ormed by an upright object held in ront o a concave mirror o ocal length + 3m. The object distance is 2.5m. Include a ray diagram. 13. Regular Problem Locate the position, orientation, and type o image ormed by an upright object held in ront o a concave mirror o ocal length +26 cm. The object distance is 32cm.

Unit 10 Reflection. Grading: Show all work, keeping it neat and organized. Show equations used and include all units.

Unit 10 Reflection. Grading: Show all work, keeping it neat and organized. Show equations used and include all units. Name: Hr: Unit 0 Relection Grading: Show all work, keeping it neat and organized. Show equations used and include all units. REFLECTION Vocabulary Relection: The bouncing o light. The angle a beam o light