Description
Students will construct and then evaluate separate components of a crystal radio, relating the electromagnetic structure of parts to the function of the component and then engineer the components into a complete, working crystal radio.
Time Requirement: 90 minutes
Grades 9–12. Using kit materials, students construct a working AM crystal radio, popular in the early days of broadcasting, to tune into local stations. They build circuit components from aluminum foil, copper wire, and cardboard tubes. Students learn how modern communication systems transmit information using electromagnetic radiation to encode a signal. A battery-powered speaker (with internal rechargeable battery) is included to amplify the radio signal for testing and listening.
During the activity, students observe energy conversion between different forms (e.g., electrical energy to mechanical energy) and build upon their knowledge of wave properties by learning:
- How transducers convert the signal’s electrical energy into a mechanical sound wave.
- The relationships between inductance, capacitance, and resonance in tuning to a radio station and building the classic LC (inductor-capacitor) tank circuit.
Designed for a class of 30 students, the kit contains materials to construct 10 functioning crystal radios and includes free 1-year access to digital resources that support 3-dimensional instruction for NGSS. A high-impedance piezoelectric earphone (item #754012), similar to the ones used with WWII-era foxhole radios, can be purchased separately.
This kit builds toward the following Performance Expectations within the Next Generation Science Standards*: Waves and Their Applications in Technologies for Information Transfer, HS-PS4-5 and HS-PS4-3; and Energy, HS-PS3-3.
The Carolina® AM Crystal Radio Kit is designed to integrate into a larger unit with lessons addressing wave mechanics, electricity, magnetism, and electromagnetism.
*Next Generation Science Standards® is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.