Science Glossary - Part 4

 SCIENCE GLOSSARY - PART 4

151.    Horizontal:    Parallel to the horizon; level.

152.    Horse power (hp):    It is a practical unit of power which equal to 550 foot-pound per second or 746 watts.

153.    Hurricane:    It is a powerful whirling tropical storm that measures 320 to 480 kilometres in diameter.

154.    Hydraulics:    It is the branch of physics that deals with the behaviour of liquids at rest and in motion.

155.    Hydrocarbon:    A compound that contains only carbon and hydrogen

156.    Hydrometer:    It is an instrument used to measures the relatives density of liquids (the density compared with that of water).

157.    Hydrosphere:    The water of the earth, ocean lakes, rivers and glaciers that cover about three-fourths of the earth’s surface.

158.    Hygrometer:    It is an instrument used to measure the amount of water vapour in the air.

159.    Hypersonic:    The sound waves which have frequencies above 500 megahertz

160.    Hypersonic speed:    The speed of an object greater than about five times the speed of sound in the fluid through which the object is moving.

161.    Hypothesis:    A tentative explanation for an observation or phenomenon. A hypothesis is used to make testable predictions.

162.    Imaging:    It is a technique by which electronics data collected by various means is converted into visual image by use of computers.

163.    Incandescence:    The production of light by materials having high temperatures & Light produced by an incandescent object

164.    Inclined plane:    A simple machine that is a sloping surface, such as a ramp

165.    Induction:    The build-up of a static charge in an object when the object is close to, but not touching, a charged object.

166.    Inertia:    The tendency of an object to remain in a state of rest of uniform motion until an external force is applied, as stated by Newton’s first law of motion.

167.    Inertia:    The resistance of an object to a change in the speed or the direction of its motion

168.    Information Technology:    It is a scientific subject, the study of how to collect, use, move, store and display information.

169.    Infrared light:    Part of the electromagnetic spectrum that consists of waves with frequencies between those of microwaves and visible light

170.    Inorganic compound:    A compound that is not considered organic. All com- pounds that do not contain carbon are inorganic, as are some types of carbon-containing compounds.

171.    Insulation:    It is the process by which the passage of electricity, heat or sound is prevented through a material.

172.    Insulator:    A material that does not transfer energy easily & A material that does not transfer electric charge easily

173.    Intensity:    The amount of energy of a wave, per wavelength. Intensity is associated with the amplitude of a sound wave and with the quality of loudness produced by the sound wave

174.    Interference:    The meeting and combining of waves; the adding or subtracting of wave amplitudes that occurs as waves overlap

175.    Ion:    An atom or group of atoms that has a positive or negative electric charge.

176.    Ionic bond:    The electrical attraction between a negative ion and a positive ion.

177.    Isomer:    Any of two or more compounds that contain the same atoms but that have different structures

178.    Isotopes:    These are atoms of an element having the same atomic number but different atomic weights.

179.    Jet lag:    It is a state of feeling unwell and exhausted experienced by air travellers when they cross several time zones in a relatively short time.

180.    Joule:    A unit used to measure energy and work. One calorie is equal to 4. 18 joules of energy; one joule of work is done when a force of one newton moves an object one meter.

181.    Kilowatt kw:    A unit of measurement for power equal to 1000 watts.

182.    Kilowatt-hour kwh:    The unit of measurement for electrical energy equal to one kilowatt of power over a one-hour period

183.    Kinetic energy:    It is a form of energy possessed by moving bodies. It is contrasted with potential energy.

184.    Kinetic theory of matter :    A theory stating that all matter is made of particles in motion

185.    Knot:    It is a unit for measuring ship’s speed.

186.    Laser:    The name stands for Light Amplification by stimulated Emission of Radiation. A device able to produce an intension narrow beam of radiation.

187.    Latent heat:    It is the heat required to change the state of a substance (for example, from solid to liquid) without changing its temperature.

188.    Latitude:    It is the distance of a point on the earth’s surface from the equator.

189.    Law:    In science, a rule or principle describing a physical relationship that always works in the same way under the same conditions. The law of conservation of energy is an example.

190.    Law of conservation of energy:    A law stating that no matter how energy is transferred or transformed, it continues to exist in one form or another

191.    Law of conservation of momentum:    A law stating that the amount of momentum a sys- tem of objects has does not change as long as there are no outside forces acting on that system

192.    Law of reflection:    A law of physics stating that the angle at which light strikes a surface (the angle of incidence) equals the angle at which it reflects off the surface (the angle of reflection). 

193.    Lens:    A transparent optical tool that refracts light

194.    Lever:    A solid bar that rotates, or turns, around a fixed point (fulcrum); one of the six simple machines

195.    Lighting conductor:    It is a conductor of electricity installed in a structure to save it from damage.

196.    Light-year:    It is a unit of distance used in astronomy. It is defined as the distance light travels through space in one year. Light travels at 300,000 km per second.

197.    Lipid:    A type of carbon-based molecule in living things. Lipids include fats and oils used for energy or as structural materials.

198.    Liquid:    Matter that has a definite volume but does not have a defmite shape. The molecules in a liquid are close together but not bound to one another.

199.    Longitudinal wave :    A type of wave in which the disturbance moves in the same direction that the wave travels

200.    Luminescence:    The production of light without the high tempera- tures needed for incandescence