# The Definition Dictionary

** Work in Progress – TEST PAGE ONLY **

Definitions are probably the most important part of Physics for the FRCA examinations. Not only do they give you something to hang your answer on, and sometimes gives you the answer to further questions, They also look amazing in a VIVA if you can give a punchy, accurate definition. That is what this page is for! All in alphabetical order!

## A

Absolute Humidity

The mass of water vapour (Grams) present per volume of air (Cubic Metre).

Ampere

‘Unit of Electrical Current; 1 ampere = 1 Coulomb/second.’

## B

Beer’s Law

‘The absorption of light is proportional to the concentration of the gas through which the light is travelling.’

Boyle’s Law

‘At a constant temperature, the volume of a fixed amount of gas is inversely proportional to its pressure.’

## C

Capacitor

‘Electrical device which stores electrical charge.’

Charles’ Law

‘At a constant pressure, Volume of a fixed amount of gas is proportional to its absolute temperature.’

Conductance

‘Conductance is the ability of the material to allow the flow of electrical charge.’

Coulomb

‘Unit of Electrical Charge; 1 Coulomb = 6.24×10ˆ18 electrons.’

## D

Damping

Damping is the ability of an object to resist oscillation in response to a force being applied to it.

Dew point

Temperature below which water will begin to condense out of air. (e.g. relative humidity reaches 100%)

Diffusion

Movement of a substance/solute from an area of high concentration to that of a low concentration

## F

‘One Farad is the ability of a capacitor to store one coulomb of charge when a potential difference of one volt is applied across it’.

## G

Gay Lussac’s Law

‘At constant volume, Pressure of a fixed volume of gas will increase in proportion to absolute temperature.’

## H

Humidity

The amount of water (vapour) present within a gas (usually air).

## I

Inductor

‘A component which opposes the flow of current by creating an electromotive force.’

## L

Lambert’s Law

‘The absorption of light is proportional to the distance the light travels through the sample.’

## M

Molality

Number of molecules of solute per kilogram of solvent

Molarity

Number of molecules of solute per litre of solution

Mole

‘a cute furry creature that lives in a hole’ or ‘6.022×10^23 molecules of a substance’

## O

Ohm

‘Unit of Resistance; 1 Ohm = Resistance across two points when one volt applied across the points gives a current flow of 1 ampere.’

Osmolality (two L’s!)

Number of osmoles of solute per kilogram of solvent

Osmolarity (one L!)

Number of osmoles of solute per litre of solution

Osmole

6.022×10^23 osmotically active particles

Osmosis

Movement of a solvent across a semipermeable membrane from a less concentrated solution to a more concentrated solution.

## P

Perfect Gas

‘A gas which obeys all of the three gas laws completely.’

## R

Relative Humidity

Ratio of water vapour present against the maximum possible (e.g. fully saturated)

Resonance

Resonance is the ability of an object to oscillate in response to a movement.

## S

Siemen

‘Unit of Conductance.’

## V

Volt

‘Unit of Voltage; 1 volt = 1 joule / Coulomb.’

Voltage/Potential Difference

‘Electrical Voltage (aka potential difference) is the energy required to move one coulomb of charge between two points in a circuit.’

## W

Watt

‘Unit of Power; Power (Watts) = Energy (Joules) / Time (Seconds).’

## Z

© Sam Beckett and Physics4FRCA, 2017. Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited.