ScienceSource.ca Dry Lab Activity

Unit D - Chapter 10

Investigating Science 10

Problem-Solving Activity

Detecting Invisible EMR - Build a Crystal Radio

Skills Reference 3

Skills you Will Use

  • Prioritizing and selecting solutions
  • Designing, building, and testing

Safety

  • Sharp Objects

Caution

You will need to use scissors, sharp objects and sharp wire in this activity. Take care never to cut or poke holes toward yourself or anyone else.

Recognize a Need

The environment is filled with many different types of invisible electromagnetic radiation (EMR), some natural, some man-made. Detecting this EMR can be very important for the functioning of certain technologies, as well as for safety.

For example, portable radios have long been popular as a form of entertainment, but there are many instances where it is extremely important to be able to detect and interpret the information radio waves carry. For example, adventurers in remote locations may only have radio signals to rely upon to get information about changing weather conditions. Another example are the many satellites and space probes that have been launched to explore our solar system and beyond. Without radio wave detection, there would be no way to communicate with these space probes.


Problem

How can you build a crystal radio to detect invisible electromagnetic radiation such as radio waves?


Materials and Equipment

  • cardboard tube
  • ballpoint pen
  • 2 - 15cm pieces of speaker wire
  • 3 - 3m pieces of speaker wire
  • wire strippers or sandpaper
  • two alligator clips
  • scissors
  • roll of aluminum foil
  • 2 - 25cm x 30cm pieces of cardboard
  • masking tape
  • crystal diode
  • earphone

Criteria for Success

  • Your crystal radio should be able to detect radio signals.

Dry Lab

A "dry lab" activity includes collected data, completed problems, or a video problem solution for your convenience. You can simply watch the following video, or if you wish to perform this lab and solve the problem for yourself, follow the procedure steps 1 through 13 described in the video. The same steps are included in written form in the documents available for download on the bottom of this page.



Communicate

  1. How well did your crystal radio work? What part or parts of the electromagnetic spectrum is your radio sensitive to? If you chose not to build the crystal radio yourself, search page 384 at ScienceSource.ca and follow some of the links to the construction of crystal radios by others.