Beyond What I Can See


Objectives:

Time Duration: one 60-minutes session

Grade Level: 6 - 8

Concepts Explored:
scientific processes, energy, systems and interactions, communication, comparison, inference, classification, sequencing, organization, measurement, evaluation and synthesis

Vocabulary:
spectrum, infrared, ultraviolet (UV) light, reflection, refraction, remote, wireless, angle, emission.

Grouping:
groups of 6 (or 8, depending on available remote controls)

Materials Per Group:

Advanced Preparation:
Have a TV/VCR available and request students to bring from home, remote controls, with parental permission (clearly labeled and identified), for this activity. (It is preferable to have universal remote controls or if not available, use VCR and TV remote controls from your school).

Teacher Resources:
Book: "Television", Christopher Griffin-Beale and Robyn Gee, Usborne Young Scientist Publication. ISBN 07460-1057-5.

Teaching Tips:
If not enough remote controls are available, instruct this lesson as a demonstration, facilitating the use of the remote controls available to a few children at a time, as a whole class presentation. (IR is short for infrared.)

Make sure the TV sound is turned off. Pre-program channels to only access those with parental control prior to this exercise.

Procedures:

  1. To test how far away will the remote control work, locate the receiver section of the TV. It might be a small plastic window. Test it starting at a close, measured distance, i.e. 10 cms. Back away from the TV set, at increments of one meter and find out how far away the remote will work. Design a graph to record your data. (For each measurement, make sure you always aim the remote control at the receiver window.)

  2. Find out what materials will stop the infrared beam from reaching the receiver. (What experiment could you do?) Brainstorm possibilities and if the following are not mentioned, facilitate controls and variables as follows:

    Place different materials in front of the path of emission. To obtain valid data, perform this test from the same distance each time. This distance should be within the range from which the IR remote can send signals to the receiver.

    What if...

    • you tape plastic, newspaper, tissue paper or aluminum foil in front of the IR remote?
    • you double the thickness of the material?

    Test which thickness of which material will stop the beam. If it appears to stop, move closer to the TV. Does it still stop it? Compare your remote's strength to someone else's.

    Devise a graph to record the data showing the materials tested and the distances at which an IR signal is received.

  3. To test what material will reflect the infrared beam, use mirrors, objects around the room, aiming in different directions. Will the IR remote work if the beam bounces off other materials? Does the TV receiver work when the objects are placed in front and the beam is bounced off them?

    Make an illustration or map of the location of the TV, the objects you tested and the path of the IR beams that worked.

    What conclusions can you draw about the location, angle and distances between the TV the IR remote and the objects from which the beam bounced?

  4. Measure the cone of emission of your IR remote or the angle of spread. Using information from your previous graph and the following technique, draw the cone of emission:
    • Put the IR remote 5-6 feet from the TV at the exact level of the receiver. (Make sure is stable and supported).
    • Put a sheet of blank paper under the remote and tape it down.
    • Line up the remote so the beam would be at a right angle, with reference to the face of the TV set exactly. The side of the TV set and the side of the remote need to be parallel to each other.
    • Draw a line along the side of the remote as a guide.
    • Place a dot on the back corner of the remote on the piece of paper.
    • Use the dot as an axis to rotate gradually in increments the remote, until it no longer makes the TV work. Draw lines as you go along.
    • o the same on the other direction.
    • How large is the cone of emission? Why is it called a cone?
Assessment:
Is the angle of emission the same side to side as it is up and down? How could you find out?

Make a chart with the types of materials that reflect infrared energy and the types that stop or weaken it. Are these the same as those that reflect/stop visible light?

Extensions:
Using UV light bulbs and sensitive paper, expose the paper with an object on top to compare it to the paper exposed to visible light. How are they the same? different? What variable played a role? Distance, time, frequency? How could you tell?


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