Physics Facts Part 4

152. What is a micrometer guage?

It is an instrument used in measuring the thichkness of a wire.

153. What is a Generator?

This is a machine to produce electric power.

154. What is the study of the physical nature of earth known as?

Geo physics.

155. What is a glider?

It is a flying machine like an aeroplane, but it has no engine.

156. What is a graduated instrument?

An instrument with marks on it, so that measurements can be mad as in a thermometer.

157. What is a gramme-calorie?

The heat that is required to raise the temperature of one gram of water from 14.5° C to 15.5°C.

158. What is meant by gravity fuel system?

The arrangement in a car by which the fuel( Petrol/ Diesel) flows into the engine by its weight.

159. What is a grease trap?

It is an instrument to trap grease from the kitchen waste into entering the drainage system and blocking it.

160. What is a hacksaw?

It is a saw for cutting metal.

161. What is a hair spring?

It is a balencing spring which oscillates and controls the working of a watch.

162. What are head phones?

These are two telephone receivers put over the ears for listening to music.

163. What is a heat exchanger?

The apparatus by which heat is transferred from one material to another, eg. from hot gas to heat water.

164. What do you mean by high frequency waves?

A current with more cycles (changing from positive to negative and vice versa), at more than 15, 000 cycles per second. This is generally used for currents produced by radio waves.

165. What s a hydrogen electrode?

In a hydrogen cell, the hydrogen electrode is used to generate positive ions. The hydrogen electrode is made by bubbling hydrogen over a platinum plate standing in a solution of dilute HCI.

166. What is hydrography?

The drawing of maps of the sea bottom for use in shipping.

167. W is the use of a hydrometer?

Hy meter is used to measure the density of a liquid.

168. What is an insulator?

These are substances which prevent loss of electricity from

169. What is knocking?

The noise generated by an internal combustion engine (Diesel engine) when unburnt gases escapes through the exhaust pipe.

170. What is meant by latent heat of a substance?

The heat content of a substance, at a critical temperature, when it passes form one state to another. E.g. Water to steam.

171. What is leaching?

The process of removing salts from the soil by using excess water.

172. What is luminescence?

The production of light in a substance without the use of heat.

173. What is a mirage?

The reflection of light by a layer of rarified air (less dense) so that the travelers in a desert think that they see water when there is none.

174. What is a mordant?

A substance (like salt) with which cloth is treated before it is dyed.

175. What is a muffle furnace?

The furnace with fire brick or clay, heated from outside, used for firing pottery.

176. What is negative resistance?

The property of parts of certain electric circuits in which the current increases rapidly while the voltage need to drive it decreases.

177. What is peak load ?

The greatest amount of electricity which a power-station has to supply, specially during the morning hours.

178. What is peak value?

An alternating current has to rise to the biggest strength, decreases to zero , then rises to biggest strength in opposite direction and son. The biggest strength in either direction is known as peak value.

179. What is a pelton wheel?

This is a power producing instrument in which cups on the wheel are struck by a jet of water to turn and produce electricity. 

180. What is a penumbra?

Penumbra is the area of partial eclipse.

181. What is a permalloy?

It is an alloy of nickel, iron and other metals which can be easily magnetized. These alloys are used to make cores of electromagnets because it easily be magnetized and demagenetised with little waste of energy.

182.What is a photoconductor?

It is a substance whose power to conduct electricity increases when light falls on it.

183. What is photo electric cell?

This is a cell which produces current by sending out electrons from a metal plate (photo emitter) when light falls on it.

184. What is meant by photo emission?

The loss of electrons from an insulated metal surface when light falls on it.

185. What is a photometer?

It is a an instrument to measure or compare the intensity of light from different sources.

186. What is a photomultiplier?

A photo multiplier is equipment in which there are two photo-emitters. The electrons from the first emitter is sent out to the next photo emitter so that more electrons are generated (secondary emission) as a result of which a stronger current is produced.

187. What is a photo voltaic cell?

A cell which consists of two electrodes composed of two different materials, like copper and copper oxide. This cell produces electric power like a battery when light falls on it.

(solar cell in the calculators).

188. What is the relevance of pitch in a musical note?

Pitch is the height of the musical wave, which is measured as no, of sound waves produced per second. Shrill sounds have very high pitches.

189. What is pitch blende?

Uranium oxide, which is the source for Radium.

190. What is a piston?

It is a solid block which moves forwards and backwards in the cylinder of an automobile engine.

191. What is a plano- convex lens?

A lens which has one side flat and the other side curved outwards.

192. What is a plasmoid?

A mass of gas, which has become so hot that all its atoms have become ions. (as seen in stars).

193. What is a plaster board?

These are sheets made of gypsum (Calcium Sulphate) between paper used to make linings for inside walls or ceilings (false roofs as seen in theaters and posh hotels), instead of plastering.

194. What is a plastisizer?

It is a solvent that is iused to dissolve plastic so that it can be moulded to the required shape.

195. What is Power Factor?

The factor by which the apparent power in an alternating current circuit is to be multiplied to obtain the true power in the circuit.

196. What is a pressure guage?

It is mechanical device which determines the pressure inside the fluid flowing system when connected with the system.

197. What is a Pressure governer?

It is a controlling device to maintain the fluid /gas pressure in a system and preventing the increase in pressure beyond the set point.

198. What is a printed circuit?

ab A printed circuit is etching the design of an electrical system on a thin copper sheet.

199. What are actinic rays?

This is a part of sunlight, which has an effect on photographic films.

200. What is an actinometer?

A is an instrument used to measure the strength of sunlight.