Thursday, August 12, 2010
science working models
science working models
240 volts is the home electricity voltage in India which is supplied to our homes. On voltage of 240 maximum appliances work but some devices like: hair dryer, battery chargers, laptops, radios etc, do not accept 240 volts for them use of voltage converter is must. Three types of voltage converters are there:-Resistors networks TransformersCombination When our appliances are turned on, a force of 240 volts is passed through appliance. The energy is used in completing the works like heating, running motor, lighting, etc it is analogous to the water is forced through the pipe using a mono block pump.primary resources maths
primary resources maths
Ecological efficiency is the percentage of energy transferred from one trophic level to the next. Alternatively, it is the ratio of the net productivity, i.e., the biomasS, at one trophic level to the net productivity (biomass) at the level below. Ecological efficiency varies among organisms. Usually it is 10%. This means that 90% of the energy available at onp trophic level never transfers to the next. (There are number of ratios used to express the efficiency with which organisms exploit their food resources and convert the food into biomass. Important efficiency measures for producers are —1. Photosynthetic efficiency. It is the percentage ratio between gross primary productivity and incident total solar radiation. It generally varies from 1 to 5 per cent.Photosynthetic efficiency_ Gross primary productivity ^ Incident total solar radiation2. Net production efficiency. It is the percentage ratio between net primary productivity and gross primary productivity. It is around 50%.Net production efficiency_ Net primary productivity Gross primary productivityImportant efficiency measures for consumers include —1. Assimilation efficiency. It is the percentage ratio between food energy assimilated and food energy ingested at one trophic level.Assimilation efficiency_ Food energy assimilated ^ ^^ Food energy ingested2. Ecological efficiency. It is the percentage ratio between energy in biomass production at one trophic level and energy in biomass production at previous trophic level. It is also called trophic level efficiency.Ecological efficiency = Energy in biomass production at one trophic level Energy in biomass production at previous trophic levelbiology study guide
biology study guide
The data gathered in the experimental study of artificial transmutations are so vast and varied that it is not possible to give here a detailed account of them ; nor can this serve any useful purpose to the general student. It is more profitable to indicate the main guiding principles used in the classification and interpretation of experimental data.life of pi summary
life of pi summary
1. Experiments show that if a discharge tube is exhausted to a low pressure (0.01 mm of Hg), cathode rays are produced.2. Cathode rays are fast moving electrons having a negative charge. They contain the smallest quantity of electricity from nature i.e., 1.602 x 10'19 coulombs.An electron has a mass 9.1 x 10~31 kg and hence is about —— limes lighter 1840than the hydrogen atom.3. Prof. J.J. Thomson proposed the hypothesis that cathode rays were streams ofnegatively charged particles. He was the pioneer who devised an experiment £by which the specific charge — of such particles was determined. m4. Milikan's oil drop experiment was the first direct experimental proof of the atomic nature of electric charge.5. The photoelectric effect is a process whereby electrons can be ejected from a metallic surface when light is incident on that surface. Einstein provided a successful explanation of this effect by extending Planck's quantum hypothesis to the electromagnetic field, in this model, light is viewed as a stream of particles called photons, each with energy E = hv, where v is the frequency and h is Planck's constant The kinetic energy of the ejected photoelectron is given by (hv - wj, where wo is the work function of the metal.6. X-rays from an incident beam are scattered at various angles by elections in a target such as carbon. In such a scattering event, a shift in wavelength is observed for the scattered X-rays, and the phenomenon is known cs the Compton effect. Classical physics does not explain this effect. If the X-rays is treated as a photonconservation of energy and momentum applied to die photon-election collisions yields the following expression for the Comptonshift:-(1-cos a), mcwhere m is the mass of the electron, c is the speed of light and a is the scattering angle.7. All matter exhibits both particle and wave character. The dualistic nature of matter was proposed by de-Broglie. The de-Broglie wavelength of any particle of mass m and velocity v is given by x = t.-±. p mv£and the frequency of matter waves obeys the Einstein relation i) = —, where hE is the total energy of the particle. Subsequent experiments that confirmed the concept of matter waves included the observation of electron diffraction by Davisson and Germer and independently by Thomson.8. The wavelengths of visible objects are far too small for their wavelike nature to be apparent in everyday life. The wavelike nature of electrons becomes visible when they are reflected from single crystals or diffracted by ultra-thin materials.pa school requirements
pa school requirements
Find the co-ordinates of a point which is equidistant from the points (-2,9), (10,-7) and (12,-5) Solution Let the co-ordinates of the required point P be (x,y) which is equidistant from the given points A(-2,9),B(10,-7) and C(12,-5) Now; $PA=\sqrt{(x+2)^{2}+(y-9)^{2}}$ $PB=\sqrt{(x-10)^{2}+(y+7)^{2}}$ $PC=\sqrt{(x-12)^{2}+(y+5)^{2}}$ Since PA=PB $\therefore PA^{2}=PB^{2}$ $\Rightarrow(x+2)^{2}+(y-9)^{2}=(x-10)^{2}+(y+7)^{2}$ $\Rightarrow x^{2}+4x+4+y^{2}-18y+81=x^{2}-20x+100+y^{2}+14y+49$ $\Rightarrow24x-32y=64$ $\Rightarrow3x-4y=8$.......(i) Also, since PA=PC $PA^{2}=PC^{2}$ $\Rightarrow(x+2)^{2}+(y-9)^{2}=(x-12)^{2}+(y+5)^{2}$ $\Rightarrow x^{2}+4x+4+y^{2}-18y+81=x^{2}-24x+144+y^{2}+10y+25$ $\Rightarrow28x-28y=84$ $\Rightarrow x-y=3$....(ii) Solving equation (i) & (ii); x=4;y=1 Hence the co-ordinates of the required point P are (4,1) Ans.how to make paper look old
how to make paper look old
ModalsExampleUses 1Can / can'tThey can control their own budgets. We can't fix it. Can I smoke here? Can you help me?Ability / Possibility 1 Inability / Impossibility Asking for permission! Request [Could / couldn'tCould I borrow your dictionary? Could you say it again more slowly? We could try to fix it ourselves. I think we could have another Gulf war. He gave up his old job so he could work for us.Asking for permission! i RequestSuggestion j 1 Future possibility Ability in the pastMayMay I have another cup of coffee?China may become a major economic power.Asking for permission 1 Future possiblity jMightWe'd better phone tomorrow, they might beeating their dinner now.They might give us a 10% discount.Present possibilityI lFuture possibility ,Must / mustn'tWe must say good-bye now.They mustn't disrupt the work more thannecessary.Necessity / Obligation / ProhibitionOught toWe ought to employ a professional writer.Saying what's right or correctShallShall I help you with your luggage? Shall we meet at 2.30 then? Shall I do that or will you?OfferSuggestion Asking what to doShouldWe should sort out this problem at once.I think we should check everything again. Profits should increase next year.Saying what's right or correctRecommending action Uncertain predictionWiU / won'tI can't see any taxis so I'll walk. I'll buy it for you if you like. I'll get back to you on Monday. Profits will increase next year.Instant decisionsOfferPromiseCertain predictionWould / wouldn'tWould you mind if I brought a colleague with me?Would you pass the salt please? Would you mind waiting a moment? "Would three o'clock suit you?" - "That'd be fine."Would you like to play golf this Friday? "Would you prefer tea or coffee?" - "I'd like tea, please."Asking for permissionRequest RequestMaking arrangementsInvitation Preferences
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