Other
Institute for Telecommunication Sciences: Resonance
This site contains a straightforward definition of resonance in an electrical circuit.
Georgia State University
Georgia State University: Hyper Physics: Voltage
Electrical currents and voltage are defined and illustrated.
NASA
Nasa: Imagine the Universe: Pulsars
Resource explores what a pulsar is, as well as what is currently known about this phenomenon. Content includes a focus on x-ray observations of pulsars, and gamma-ray pulsars.
CK-12 Foundation
Ck 12: Physical Science for Middle School
This digital textbook covers core physical science concepts and includes interactive features, real world examples, and videos.