Wikijunior:How Things Work/Glossary

Force

 * Force &mdash; An expression of the ability to push, pull, twist or accelerate a body.
 * Mechanical Advantage &mdash; The ratio of the force produced by a machine to the applied input force.
 * Work &mdash; A measure of energy expended in moving an object. Force times distance equals work (F*D = W).



Motion

 * Motion &mdash; The body said is in motion if its position changes with respect to time.
 * Rest &mdash; A body said to be in rest if its position does not changes with respect to time.
 * Distance &mdash; It is the length of the actual path traversed by the body between its initial and the final positions.
 * Displacement &mdash; It is defined as the change in the position of the object in a fixed direction.



Electricity

 * Electricity &mdash; Electricity is the flow of electrons in a conductor.
 * Ohm &mdash; The SI unit measuring the electrical resistance.
 * Mega-ohm &mdash; A unit of electrical resistance which is equal to one million ohms.
 * Ampere &mdash; The basic SI unit measuring the quantity of electricity.
 * Ohmmeter &mdash; Ohmmeter is an instrument for measuring resistance in a conductor. The unit used is in ohms.
 * Mega-ohmmeter &mdash; An instrument for measuring extremely high resistance. The unit used is mega-ohm.
 * Ammeter &mdash; An electric meter used to measure current. The unit used is in amperes.
 * Voltmeter&mdash; A voltmeter is an instrument used for measuring the potential difference (voltage) between two points in an or electronic circuit.
 * Voltage Drop &mdash; The loss of voltage between the input to a device and the output from a device due to the resistance of the device.
 * Potential Difference &mdash; The difference in electrical potential (voltage) from one point in an electric circuit to another point.
 * Direct Current (DC) &mdash; The current flowing in one direction only.
 * Alternating Current (AC) &mdash; The current flow which first goes one way and then reverses it's direction at regular time interval.
 * Battery &mdash; These are devices which convert chemical energy into electric energy.