Lens Inquiry A CfAO/ISEE Designed Laboratory Hartnell Community College September 2009

Inquiry Inquiry is modeled on how scientists actually perform their research, with no one to tell them what to investigate or how to carry out their investigations. Inquiry involves making observations, developing questions, designing experiments, making and testing predictions, recording results, reflecting on, summarizing and communicating your understanding. Inquiry can be challenging, but it can also be rewarding.

Activity Overview Demonstrations of a few phenomena involving lenses. You will have a short period of time to get familiar with the materials and test these out while writing down vocabulary. We will compile vocabulary as a class and you will choose a question to investigate to explain one of the phenomena that you observed. You will have 50 min to conduct your investigation. You will present your findings to the class. You will build a telescope using what you learned in your investigations and the presentations.

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Why Use Telescopes? You can see many objects in the sky using only your eyes, as you have done in previous lab activities, but using an astronomical telescope allows you to see: – More detail in the bright objects – Many objects that are too faint to even detect using only your eyes

Astronomers rely on Telescopes Telescopes improve our vision of the objects of study in a number of ways: – make the object appear larger – make the object appear sharper – make the object appear brighter

As technology evolves, telescopes become more advanced and allow us to see more detail in a range of astronomical objects.

State-of-the Art Famous Telescopes The Hubble Space Telescope 2.4m Primary Mirror Keck: 10m Reflecting Telescopes

These telescopes are currently being used by professional astronomers to conduct forefront research. Historically telescopes have been instrumental to our discovery of what lies beyond our own planet.

Things Inside our Solar System SaturnNeptune Credit: Saturn G. S. Orton & P. A. Yanamandra-Fisher (JPL), Keck Observatory, NASA, Uranus Lawrence Sromovsky, (Univ. Wisconsin- Madison), Keck Observatory, Neptune AO Staff, Keck, LLNL Astronomy Picture of the Day: Uranus

Things inside our own galaxy, the Milky Way M16: Pillars of CreationNGC 1499: The California Nebula Credit: M16 J. Hester, P. Scowen (ASU), HST, NASA NGC 1499 Caltech, Palomar Observatory, Digitized Sky Survey; Courtesy: Scott Kardel

Other galaxies Credit & Copyright: M31 Robert Gendler (robgendlerastropics.com) Hubble Ultra Deep Field S. Beckwith & the HUDF Working Group (STScI), HST, ESA, NASA M31: The Andromeda GalaxyThe Hubble Ultra Deep Field

To understand how telescopes work, we will concentrate on a particular type of telescope called a refracting telescope that uses lenses.

Refracting Telescopes Located Nearby: 36 inch Refractor at Lick Observatory 20 inch Refractor at Chabot Space and Science Center

What’s Inside? This simple telescope is made up of two lenses. To simplify the problem we would like for you to learn how a single lens works in an inquiry activity.

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Light Travels in Straight Lines But… it can change directions when moving from one medium to another Index of refraction (n): a property of the medium (glass/liquid/etc) that determines how the light travels through it The larger the change in speed, the more the light is bent Snell’s Law: n 1 sin(angle 1 ) = n 2 sin(angle 2 )

Image Brightness The LARGER the lens the BRIGHTER the Image The shape of aperture doesn't matter, just the amount of light that gets through

Focal Point The curvature of the lens bends light toward a special focal point which is different for different lenses Higher curvature means more bending means shorter focal length A completely flat lens will not bend light at all If the object is at infinity, the image is located at the focal length of the lens

Object and Image Distances Combined with the focal length of the lens, these distances can be predicted using the lensmaker's equation 1/(image distance) = 1/(object distance)+1/(focal length)

Putting Two Lenses Together Separation: sum of the two focal lengths

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Activity Timeline 6:00-6:10 Introduction 6:10-6:15Demos involving Lenses 6:15-6:25Starters 6:25-6:35Discussion of Vocab and Generate Questions 6:35-6:40Choose question to investigate and form groups (3-4 people) 6:40-7:30Focused Investigation 7:30-7:45Make a poster to answer your question 7:45-8:15Sharing out: each group will have 2 minutes to present 8:15-8:25Converging Lenses Synthesis 8:25-8:45Telescope Activity 8:45-8:50Final Synthesis

Layout

State-of-the Art Famous Telescopes Trade-offs Both Reflecting Telescopes (Mirrors) Hubble has a 2.4m Primary, but is in Space Each of Keck’s 10m primary mirrors is composed of 36 hexagonal segments that work together as a single piece of reflective glass. The Hubble Space TelescopeKeck: 10m Reflecting Telescopes

Challenger Telescope at Fremont Peak Observatory 30” Diameter f/4.8 Newtonian on an English cross-axis equatorial mount First light in 1986

Activity Timeline 2:00-2:10 Introduction 2:10-2:15Demos involving Lenses 2:15-2:25Starters 2:25-2:35Discussion of Vocab and Generate Questions 2:35-2:40Choose question to investigate and form groups (3-4 people) 2:40-3:30Focused Investigation 3:30-3:45Make a poster to answer your question 3:45-4:15Sharing out: each group will have 2 minutes to present 4:15-4:25Converging Lenses Synthesis 4:25-4:45Telescope Activity 4:45-4:50Final Synthesis

Activity Timeline 3:00-3:10 Introduction 3:10-3:15Demos involving Lenses 3:15-3:25Starters 3:25-3:35Discussion of Vocab and Generate Questions 3:35-3:40Choose question to investigate and form groups (3-4 people) 3:40-4:30Focused Investigation 4:30-4:45Make a poster to answer your question 4:45-5:15Sharing out: each group will have 2 minutes to present 5:15-5:25Converging Lenses Synthesis 5:25-5:45Telescope Activity 5:45-5:50Final Synthesis