Chapter 5, Section 7

February 15, 2011 HW: PTG 5.7, p 555, #1-6, 8, Due Fri  Learning Objectives Compare and contrast real and virtual images Describe focal length  Success Criteria Identify the focal point and the focal length of a curved mirror Observe virtual images in a convex mirror Observe real and virtual images in a concave mirror Measure and graph image distance vs. object distance for a concave mirror  Do Now: 5.6 Quiz Write LO and SC on new left page p 548 WDYS/WDYT  Agenda: Do Now Lab 5.7 Summary

Investigation 5.7  #1 and #2  #3-9  #10-12  Record observations with concave and convex mirror  Class demo under document camera. Students record responses for #8 and #9  Students complete using same steps as 3-9.

February 16, 2011 HW: PTG 5.7, p 555, #1-6, 8, Due Fri  Learning Objectives Compare and contrast real and virtual images Describe focal length  Success Criteria Identify the focal point and the focal length of a curved mirror Observe virtual images in a convex mirror Observe real and virtual images in a concave mirror Measure and graph image distance vs. object distance for a concave mirror  Do Now: Read procedures Set up Notebook  Agenda: Do Now Physics Talk 5.7 Summary

Investigation 5.7 continued  #13-15 Teacher demo with finding image  # Students use same process with object that is outside window  Students record observations in data table like the one found in #14  Students record observations in journal and thoughts on convex mirrors

February 17, 2011 HW: PTG 5.7, p 555, #1-6, 8, Due Fri  Learning Objectives Compare and contrast real and virtual images Describe focal length  Success Criteria Identify the focal point and the focal length of a curved mirror Observe virtual images in a convex mirror Observe real and virtual images in a concave mirror Measure and graph image distance vs. object distance for a concave mirror  Do Now: How do the images of concave and convex mirrors compare? How do you know?  Agenda: Do Now Physics Talk 5.7 Summary

Physics Talk 5.7  What is a real image?  What is a virtual image?  An image that will project on a screen – it has an actual image location  An image that will not project on a screen – the image only appears to be coming from that location

Physics Talk 5.7  What is a concave mirror?  What is a convex mirror?  A curved mirror in which the reflecting surface caves in  A curved mirror in which the reflecting surface bulges out

Physics Talk 5.7  What is the relationship between the angle of incidence and angle of reflection?  The angles are equal. This allows us to draw ray diagrams that illustrate how the light is moving

Studying Ray Diagrams  Illustrating light 3 rays coming toward concave mirror  1. This ray is parallel to principal axis. This same ray reflects through the focal point  2. This ray approaches the center of the mirror and reflects with the same angle  3. This ray goes through focal point first, hits the mirror, and reflects parallel to the principal axis All 3 rays must be present in ALL ray diagrams!!!

Studying Ray Diagrams  The place where all 3 rays meet is the top of the image  The rest of the image is between that point and the principal axis All 3 rays must be present in ALL ray diagrams!!!

Study the Diagram  This is a similar situation, except the object is farther from the mirror  This demonstrates the different sized images you saw in the lab Find and name all three rays

Diagram with Virtual Image  If the object is closer to the mirror than the focal length, it will produce a virtual image

Diagram with Virtual Image  1. This ray runs parallel to the principal axis and through the focal point  2. This ray goes from the object in the angel of the focal point and will reflect parallel to the principal axis  3. This ray will leave the object and reflect off the mirror where the principal axis and mirror meet with the same angle Where do the rays meet?

Physics Talk 5.7  Where did the rays meet in the diagram?  Where can the image be found?  The rays never met, which means there is no real image!  The virtual image appears to be behind the mirror where the extended rays meet

Physics Talk 5.7  How does this compare to plane mirrors?  With plane mirrors, the virtual image is identical in size to the object  With curved mirrors, the virtual image can be a different size

Physics Talk 5.7  How does this work for convex mirrors?  Find the rays

What kind of relationship is it?  We can tell by looking at the graph, that it has the shape of a hyperbola.  This shape tells us we have an inverse relationship between object distance and image distance

Summary  Checking Up p 552  Essential Questions p 554 What does it mean? How do you know? Why should you care?  LO and SC reflections

Practicing Ray Diagrams PTG #7, 9-12 as a class

Ray Diagram Practice Worksheet