## aberration Quick reference

### A Dictionary of Physics (7 ed.)

1. (in optics) A defect in the image formed by a lens or curved mirror. In chromatic aberration the image

## band theory Quick reference

### A Dictionary of Physics (7 ed.)

The theory that, in crystals, electrons fall into allowed *energy bands, between which lie forbidden bands. Although *

## barometer Quick reference

### A Dictionary of Physics (7 ed.)

A device for measuring *atmospheric pressure. The mercury barometer in its simplest form consists of a glass tube

## Beckmann thermometer Quick reference

### A Dictionary of Physics (7 ed.)

A thermometer for measuring small changes of temperature. It consists of a mercury-in-glass thermometer with a scale covering only 5

## big-bang theory Quick reference

### A Dictionary of Physics (7 ed.)

Newton’s work gave a mathematical basis for the universe on a large scale. However, the data available at the time

## Carnot cycle Quick reference

### A Dictionary of Physics (7 ed.)

The most efficient cycle of operations for a reversible *heat engine. Published in 1824 by N. L. S.

## Cartesian coordinates Quick reference

### A Dictionary of Physics (7 ed.)

A system used in analytical geometry to locate a point *P*, with reference to two or three axes (see

## cathode-ray tube Quick reference

### A Dictionary of Physics (7 ed.)

The device that provides the viewing screen in the television tube, the radar viewer, and the *cathode-ray oscilloscope.

## celestial sphere Quick reference

### A Dictionary of Physics (7 ed.)

The imaginary sphere of infinite radius within which celestial bodies appear to lie. The earth, and the observer, are visualized

## circle Quick reference

### A Dictionary of Physics (7 ed.)

A closed curve every point on which is a fixed distance (the radius) from a point (the centre)

## complex number Quick reference

### A Dictionary of Physics (7 ed.)

A number that has a real part, *x*, and an imaginary part, i*y*, where i=√−1 and *x*

## crystal defects Quick reference

### A Dictionary of Physics (7 ed.)

A crystal *lattice is formed by a repeated arrangement of atoms, ions, or molecules. Within 1 cubic centimetre of

## crystal system Quick reference

### A Dictionary of Physics (7 ed.)

A method of classifying crystals on the basis of their unit cell. There are seven crystal systems. If the cell

## decay sequence Quick reference

### A Dictionary of Physics (7 ed.)

A plot of neutron number (*N*) against proton number (*Z*) for nuclides belonging to a particular

## E Quick reference

### A Dictionary of Weights, Measures, and Units

*Metric* As an upper-case prefix, E, see exa-, e.g. Eg = exagram.

mathematics. As E, initial

## earth’s atmosphere Quick reference

### A Dictionary of Physics (7 ed.)

The gas that surrounds the earth. The composition of dry air at sea level is: nitrogen 78.08%, oxygen 20.95%, argon

## eclipse Quick reference

### A Dictionary of Physics (7 ed.)

The total (total eclipse) or partial (partial eclipse) obscuring of light from a celestial body as

## elasticity Quick reference

### A Dictionary of Physics (7 ed.)

The property of certain materials that enables them to return to their original dimensions after an applied *stress has

## Electrical Conductivity in Metals Quick reference

### A Dictionary of Physics (7 ed.)

Elementary conductivity theory is an extension of *free-electron theory, in which the electrons in a metal are treated

## electric bell Quick reference

### A Dictionary of Physics (7 ed.)

A device in which an electromagnetically operated hammer strikes a bell. Pressing the bell-push closes a circuit, causing current to