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Building LED “Candles” for Grade 10 Optics

Richard Taylor, retired Physics teacher, Ottawa Carleton District School Board
Richard@teya.ca

“Brrrriiinngg! Hello, Richard? I was just cutting up some candles to use in the grade 10 optics labs and I got thinking about those cute little LED things you made. Do you think you could make some more for me?”

Certainly I remembered the grade 10 optics labs! Carefully prepping all those candles and optical benches, carefully priming the students to use the candles. Turn out the classroom lights and then the chaos begins. Matches breaking, fingers and hair getting singed, wax spilled on lab benches and floors (amazingly slippery!), images too dim to be seen, and which way up is that candle flame image anyway?

Several years ago, I came up with a better idea: mounting a red and a green LED on top of a 9 V battery. The LEDs produce about the same amount of light as a candle, and having the two different colours makes it easy to see whether an image is upright or inverted. After building 15 more of these, I thought it was about time to share the instructions so that other teachers can build their own. Read More...

Rich Problem-Solving Challenges for Virtual Students

Chris Meyer
Past-President, OAPT
Chris_meyer1@sympatico.ca

Shining the Light on Grade 10 Optics (Part 2)

President, Ontario Association of Physics Teachers
Assumption College Catholic High School

This article continues from the initial article I wrote on optics, which detailed many of the misconceptions that students struggle with but are hidden inside the simple mathematics of the unit. In this article I look at practical ways for making the optics unit more interactive, with a focus on developing the rules for ray diagrams and the cooperative group problem solving I have my students complete at the end of the unit. Read More...

Shining the Light on Grade 10 Optics

Vice President of Teaching and Learning, Ontario Association of Physics Teachers
Department Head of Science, Assumption College Catholic High School

This article is the first in a two-part series surrounding the development of an inquiry-based optics unit for grade 10 Science. The focus of this first article is to provide the reasoning why inquiry-based optics is needed in Science 10 and some of the important ideas that I introduce to help battle the preconceptions students hold.

I taught Science 10 for the first time in a while last year, and I have it again this year (by request). After changing the way I taught Physics 11 and 12 to a more inquiry-based style, I decided to do something similar with Science 10. This in turn led me down a path towards more effectively introducing optics to my students. In speaking with other teachers, I quickly found that the simplicity of the mathematics in the optics unit can often mask serious conceptual difficulties. I began to look at what Physics Education Research had to say about the common conceptual misunderstandings and came across the following series of questions asked by Goldberg and McDermott in their 1987 paper [1].    Read More...

A Ghostly Hologram

Saara Naudts, Physics Teacher (Peel District School Board)
saara.naudts@icloud.com

When I was looking at a quick and fun activity to spark students’ interest in optics, I came across several "how to turn your smartphone into a 3D hologram" videos. It shows how when you place a small, clear pyramid on your phone's screen playing a specially created “hologram” video, the video appears floating above your phone within the pyramid.

Intrigued, I wondered if this was just another internet hoax as I couldn't understand how a hologram can be created using a smartphone, but a colleague overheard my questioning and affirmed she heard from a teacher's friend's friend that this works! Hmmm... I wasn't really oozing confidence after that answer, so I tried building one myself. Read More...

Mirrors and Ray Diagrams App for Grade 10 Science

Matthew Craig, Teacher at the Community Hebrew Academy of Toronto
matt.simon.craig@gmail.com

I’ve been programming a suite of PC/MAC/Android simulations designed for teaching the Ontario curriculum for science and physics. Previously, I wrote about a Metal Leaf Electroscope Simulator.

In this article I am introducing a simulation I use to teach mirrors and ray diagrams in grade 10 optics. PhET has a simulation for refraction and one for lenses but there is nothing for mirrors, so I developed this simulation for grade 10 optics. Read More...

Schlieren Photography

Richard Taylor, Teacher Merivale High School, Ottawa

Just before the end of the last school year, I saw this video on the Veritasium YouTube channel. I found it fascinating that such a simple setup could highlight such small variations in refractive index. But is it really so simple to set up? Could this be done in the classroom? My summer project was to investigate Schlieren photography.

Total Internal Reflection

Diana Hall, Bell High School, Nepean, Ontario

A fun example of total internal reflection can be created with an aquarium tank or similar transparent container filled with water. Students enjoy wandering around the tank with objects placed around on all sides including above and below. Sometimes you can see what you appear to be looking at and sometimes not. Students are challenged to draw ray diagrams to show why you cannot see certain objects but can unexpectedly see others from certain angles. One example is shown here. It’s definitely a good seed for discussion. Probably a good coffee table display for your parties too. Read More...

Classroom Demonstration of Spectra

Jim Hunt, Physics Department, University of Guelph
phyjih@physics.uoguelph.ca

The availability of large sheets of plastic replica gratings has greatly increased the ability to show spectra to classroom-sized groups and, in the process, put on a nice light-show. Read More...

Two-Minute Impromptu Demos

Ed van den Berg and Rosea van den Berg, University of San Carlos, Talamban Campus, Cebu City, Philippines
edberg@durian.usc.edu.ph

This article was excerpted (with the authors’s permission) from a longer article in The Physics Teacher (Sept. 1998, p.356-8).

What can we do to have clear and exciting lessons without a great amount of demonstration apparatus and hours of preparation each day? We present here a collection of small and quick demos that require no equipment beyond what is present in a classroom (chalk, chairs, students, books, paper, backpacks and their contents). Some are to prove something, but most are to illustrate, visualize, or simulate. These basic and well-tried ideas will stimulate students and revive the instructor who has spent a late night checking student papers. Have fun! Read More...

Reflections

George Vanderkuur, Malvern Collegiate, Toronto

A laser, chalk dust and right-angle corner made of mirror tiles show the retro-reflection of light from a corner cube mirror. (Safety note: use a low-power laser beam and take care to avoid directing the beam into the audience.) Students will also enjoy looking into the mirror and observing that the image of their face (or open eye) is always in the corner. Try this with one eye closed. Read More...

Optics, Density, Holography, and Curve-Fitting

Dianne Ness, Humberside C.I.

Four demonstrations from Dianne Ness. Read More...

Colour Mixing the Economical Way

Bill Konrad, Chatham Kent Secondary School

I am sure that, in the schools of Ontario, the range of equipment presently in place to demonstrate colour mixing varies all the way from ray boxes with colour filters to expensive projectors specifically designed for that topic. Many of these may be effective but frequently one finds that the resulting colour is not exactly what theory predicts. For example, a blue light, a green light, and a red light projected onto the same area of a white screen may produce a “yellow” white or a “greyish” white. The demonstration described below gives excellent results and, in keeping with current budget constraints, is very economical. To carry it out, proceed as follows. Read More...

Parallax and Images

T.J. Elgin Wolfe, Faculty of Education, University of Toronto

Parallax is the apparent motion of one object with reference to a second object caused by a change in position of the viewer. Involve the class in the following way to introduce this concept. Read More...

Virtual Image Formed by a Plane Mirror

T.J. Elgin Wolfe, University of Toronto

An interesting demonstration that makes use of the location of the virtual image formed by a plane mirror can be done with a black cloth, a small candle (about 2 cm in height), a dull dark opaque shield about 3.5 cm tall and bent at right angles, a large pane of thin window glass, two retort stands, 4 adjustable clamps, a 400 mL beaker, and coloured water. To highlight the beaker in the dim light, outline the outer edges (as viewed by the class) with masking tape. Read More...

Real Image Demonstration

Don Murphy, Sydenham High School

Many demonstrations can be made not just interesting but truly memorable by “setting up” the students a bit beforehand. A rather well-known demonstration involves a real flowerpot and a flower suspended upside down inside a box placed 2 focal lengths in front of a large concave mirror. The viewer sees an illusion of the flower being on top of the box but the image disappears when the viewer approaches too close. The apparatus on hand at our school for a similar demo is illustrated below, but in this case a real image of a light bulb is formed. Read More...