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Abstract

What do the radio, TV, radio controlled cars, and cell phones all have in common? They all use invisible waves to transmit information. Find out which materials block radio waves, and which materials allow radio waves to pass through by doing this experiment.

Summary

Areas of Science
Difficulty
 
Time Required
Very Short (≤ 1 day)
Prerequisites
None
Material Availability
Readily available
Cost
Low ($20 - $50)
Safety
No issues
Credits

This project was adapted from a student project submitted to the Marin County Science Fair in California.

Sara Agee, Ph.D., Science Buddies

Objective

Test different materials to see if they block radio waves.

Introduction

What do the radio, TV, radio controlled cars, and cell phones all have in common? They all use invisible waves to transmit information. These waves, called radio waves, are a type of electromagnetic radiation. Radio waves are not harmful, in fact they are an extremely useful method of global communication. Two essential components for this type of communication are a transmitter and a receiver (PBS, 1998):

The ability of a wave to travel through a material is called transmittance, and materials can be divided into good transmitters and poor transmitters. One very good transmitting material for radio waves is the air in our lower atmosphere, which is why radio waves can be transmitted through the air over very long distances. One poor transmitter is the ionosphere of the earth, the uppermost layer of the earth's atmosphere which contains high energy, ionized radiation from the sun. Radio waves that are reflected by our ionosphere stay within the inner atmosphere of the earth, as shown in Figure 1, below. This phenomenon is what makes radio waves so great for global communications, because radio wave signals stay close to the surface of the earth:

Diagram on how radio waves interact with the ionosphere

The ionosphere is made of 3 layers labeled D, E, and F. Those layers interact with AM radio frequencies and cause radio broadcasting stations to adjust their power output accordingly. The D layer is closest to the ground and absorbs AM radio waves very well. However, the D layer disappears during the night and the E and F layers reflect AM radio waves which allows them to spread further with less power.

Figure 1. This figure shows how the upper layers of the earth's ionosphere (composed of the D, E and F layers) reflect and propagate radio waves transmitted from an AM radio antenna. (image © 2007, Thompson Higher Education)

Like the earth's ionosphere, being a poor transmitter is not always a bad thing. Materials which are poor transmitters are sometimes useful because they can block radio waves from moving through them and become insulators. One way to test different materials is to use a radio controlled (RC) car. You will wrap the RC car remote control, the transmitter, with different materials to find out which materials block radio waves, and which materials allow radio waves to pass through. Which materials make good or bad transmitters?

Terms and Concepts

Questions

Bibliography

  • Read this tutorial on the transmission of radio waves, or if you have Shockwave you can try the Radio Transmission Activity from PBS:
    PBS, 1998. A Science Odyssey: You Try It: Radio Transmission, PBS Online, WGBH: Boston, MA. Retrieved June 6, 2007.
  • You can read about radio waves in this Wikipedia article:
    Wikipedia contributors, n.d. Radio waves, Wikipedia, The Free Encyclopedia. Retrieved June 6, 2007.
  • Here is a brief discussion about the transmittance of radio waves vs. light waves:
    NEWTON, n.d. Ask A Scientist: Radio Wave Transmittance, NEWTON Ask a Scientist Program, Argonne National Laboratory, Division of Educational Programs, Chicago, IL. Retrieved June 6, 2007.

Materials and Equipment

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Experimental Procedure

  1. Wrap the RC car remote control in the first material you want to test, using multiple layers so that it is completely and securely covered.
  2. Attempt to operate the RC car using the remote control. Does it work?
  3. Repeat this process for each different material, collecting data in a data table:
Name of Material Does the Car Work? (Y/N) My Observations:
Aluminum Foil    
Cotton    
Paper    
Etc...    
  1. Divide the materials into good and bad transmitters based upon your results.
icon scientific method

Ask an Expert

Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Variations

  • Use a stop watch to time your test drive over a set distance. Compare the average time for remote controls wrapped in different materials. Do some go faster or slower? What might this tell you about the transmission of the radio signal?
  • You can do a similar experiment using other remote control devices, like your TV or stereo remote. How do different devices respond? Do you think they use similar or different types of waves?
  • For an advanced project, try broadcasting different frequencies from an old HAM radio. Wrap a receiver with different materials and compare transmittance at different frequencies. Do different frequencies pass through better than others?

Careers

If you like this project, you might enjoy exploring these related careers:

Career Profile
Radio frequency engineers help make sure that information gets from one place to another. This information is transmitted wirelessly as radio waves between electronic devices. Anything you can wirelessly send from one computer to another, listen to on the radio, download on a mobile phone, or see on the television (not connected to cable) is sent wirelessly using radio waves, and the transmission and devices were designed by a radio frequency engineer. Radio frequency engineers are typically… Read more
Career Profile
What makes it possible to create high-technology objects like computers and sports gear? It's the materials inside those products. Materials scientists and engineers develop materials, like metals, ceramics, polymers, and composites, that other engineers need for their designs. Materials scientists and engineers think atomically (meaning they understand things at the nanoscale level), but they design microscopically (at the level of a microscope), and their materials are used macroscopically… Read more

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Cite This Page

General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Science Buddies Staff. "Wave Blockers." Science Buddies, 20 Nov. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/MatlSci_p036/materials-science/wave-blockers. Accessed 19 May 2022.

APA Style

Science Buddies Staff. (2020, November 20). Wave Blockers. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/MatlSci_p036/materials-science/wave-blockers


Last edit date: 2020-11-20
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