A Dictionary of Science: comprising Astronomy, Chemistry, Dynamics, Electricity, Heat, Hydrodynamics, Hydrostatics, Light, Magnetism, Mechanics, Meteorology, Pneumatics, Sound, and Statics

Electricity and Magnetism

Negative Specific Heat in Astronomy, Physics and Chemistry

Starting from Antonov’s discovery that there is no maximum to the entropy of a gravitating system of point particles at fixed energy in a spherical box if the density contrast between centre and edge exceeds 709, we review progress in the understanding of gravitational thermodynamics. We pinpoint the error in the proof that all systems have positive specific heat and say when it can occur. We d...

A new connection between electricity and magnetism

Electricity arises from the flow of electron charge, ferromagnetism from the ordering of electron spins. The interactions between electricity and ferromagnetism have been crucial to our technological development over the last centuries: the magnetic fields generated by electrical currents and the voltages generated by moving magnets are two cornerstones of our modern lifestyle. Important applic...

Evaluating an electricity and magnetism assessment tool: Brief electricity and magnetism assessment

The Brief Electricity and Magnetism Assessment BEMA , developed by Chabay and Sherwood, was designed to assess student understanding of basic electricity and magnetism concepts covered in college-level calculus-based introductory physics courses. To evaluate the reliability and discriminatory power of this assessment tool, we performed statistical tests focusing both on item analyses item diffi...

DICTIONARY OF GEOPHYSICS, ASTROPHYSICS, and ASTRONOMY

index notation A notation of ten-sors in terms of their component index structure(introduced by R. Penrose). For example, thetensor T (θ, θ) = T ba θ ⊗ θb is written in theabstract index notation as T ba , where the indicessignify the valence and should not be assigneda numerical value. When components need tobe referred to, these may be enclosed in matrix<lb...