Physics
Chapter 25: 1-6 Assignment
Homework
Physics 25: 1-6 Optical Instruments
Homework
- Reading Preparation
- Key Equations
- WebLecture
- Study Activity
- Chat Preparation Activities
- Chapter Quiz
- Lab Work
Reading Preparation
Text Reading: Giancoli, Physics - Principles with Applications, Chapter 25: Sections 1 to 6
Study Points
Study Points
- Section 1: Cameras focus light on a detector surface which may either be a film with a chemical coating that reacts to light, or a photosensitive electrical surface (charge-coupled device or CCD) that measure light wavelength and intensity. In digital cameras, these measurements are stored as codes for a given area of the picture (picture element or pixel).
- Section 2: The human eye focuses light through the cornea (primary area of focus) and the lens (fine adjustments). Failure to focus correctly can result in nearsightedness (objects focus in front of the retina, and far objects are out of focus), or farsightedness (objects focus behind the retina, and near objects are out of focus).
- Section 3: A magnifying glas uses a simple lens to enlarge the image reaching the human eye. Actual magnification must include the eye's location and focus.
- Section 4: Astronomical refracting telescopes use an eyepiece for fine focus and magnification adjustments, and a primary lens for magnification. Reflecting telescopes may incorporate a series of mirrors and lenses to increase focal length within a given physical telescope, or direct light to special detectors.
- Section 5: The compound microscope uses multiple lenses to drastically increase magnification of a near object.
- Section 6: Aberration is the deviation from a perfect focus. Spherical aberration occurs when non-parallel rays focus at different points, creating a circle of confusion or fuzzy image. Chromatic aberration occurs when light of different wavelengths focusses at different distances. Other forms of aberration are due to off-axis light striking different areas of the lens at different angles (coma, of-axis astigmatism).
Key Equations
| Concept | Formula | Application |
|---|---|---|
| f-stop Ratio of focal length to lens diameter | Indicates shutter speed required for exposure | |
| Magnification at N (usually 25cm) | Magnification perceived by single-lens magnifying glass for relaxed human eye | |
| Telescope magnification | Magnification achieved by Keplerian telescope. | |
| Microscope magnification | ||
| Magnification achieved by compound microscope |
Web Lecture
Read the following weblecture before chat: Microscope and Telescope Optics
Study Activity
Use interactive exercise on bending light below to explore reflection and refraction.
- How does changing the density of the initial and final media change the direction of the ray? What happens as the density of the final medium changes? How much light is refracted? How much light is reflected?
- Use the prism exercise to explore how change in wave length changes refraction behavior.
- Use the "more tools" option to explore how waves can be used to explain how rays are bent when entering a denser medium.
Chat Preparation Activities
- Forum question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
- Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.
Chapter Quiz
- The chapter quiz is not yet due.
Lab Work
If you want lab credit for this course, you must complete at least 18 labs; you may complete more if you are preparing for the AP exam.. One or more lab exercises are posted for each chapter as part of the homework assignment. We will be reviewing lab work at regular intervals, so do not get behind!
- Lab Instructions: A Simple Telescope
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