Exam 2 practice problems solutions

# At the right face the red light has the smallest

• Notes
• 21
• 100% (8) 8 out of 8 people found this document helpful

This preview shows 17 out of 21 pages.

At the right face, the red light has the smallest angle of incidence, which means it is the least likely to experience total internal reflection. I need to determine the critical angle for the red light. F 75 i1 75 r1 i2 r2

Subscribe to view the full document.

1 c 1.00 sin 48.3 1.34 In order for the incident angle on the right face to have this value, the refraction angle at the top face must be 90 48.3 41.7    . In order for that to happen the incident angle at the top face must be i1 i1 r1 r1 1 1 r1 r1 i1 i1 sin sin 1.34 sin 41.7 sin sin sin 63.1 1.00 n n n n As long as the incident beam hits the top face at this angle or less, total internal reflection will happen at the right face. 27. The focal length of an iPhone 3GS’s camera lens is 3.85 mm. The camera is able to create a sharp image on the CCD (the sensor that plays the role of film in a digital camera) when the object being focused on is anywhere from 2.0 cm to infinitely far from the lens. In order to deal with objects at different distances from the camera the lens moves closer/further from the CCD. a. Determine the range of motion of the lens. b. Draw a ray diagram for when the object is 2.0 cm from the lens. c. No camera is able to take a sharp picture of an object located closer to the lens than the focal point. Explain why, and include a ray diagram. To determine the range o f motion (meaning, the distances from the CCD the lens can be) I’ll use the thin lens equation, once for the furthest possible object and once for the closest. Since the image forms on the CCD, i d is the quantity I’m interested in: 1 1 i, furthest o 1 i, closest 1 1 1 1 3.85 mm 3.85 mm 1 1 4.77 mm 3.85 mm 20 mm d f d d So, the lens only needs to range from 3.85 mm to 4.77 mm (just 0.92 mm!) to be able to focus on objects 2.0 cm to infinitely far away. A ray diagram is shown here for when the object is 2.0 cm away. When the object is closer to the lens than the focal point the lens produces a virtual image on the same side of the lens as the object. Only real images can be recorded by a physical device, which means camera can’t record images of objects that are this close to the lens. A ray diagram for this case is shown here.

Subscribe to view the full document.

k=
You've reached the end of this preview.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern