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PRE-BOARD ENAMINATION 2020-21 FIRST THE CLASS N(1csE) sCIENCE Paper- PHYSICS Maximunm marksi S Time: Two bours Tnstructions: Anwer ou be wrinten to this paper m r NOT will the e alloned t0 wwile on the ortswer durg the furst 13 qucstion popor reading ne tume gen ar he t a d scrpt proviided separatey dhe of tas paper time to e T h time mimtes, allowed for wriling spent in the n r e r s onder be answerod m the comect muxt a n d roll "All ilbsections of each quetion your n a o e on the question paper xcpr write anything brackets Please do not or purts of questions aregiven quesziona h e inicnded murks for Jram S e c i o n umbr in SectionI it complulsory Artempt amy four queation SECTIONI40marks this Attompt all questions from Question boidy a) Statc two conditions when The work done ty fic lder ( fuit to a ia be Secion equilibriumm n takesacath hu is orickot Degalve Lplan (e) Can the centre ot gravily ofa body be the velocity situated outade ts masct in materiaf? Cive an (21 example (d) Amac hine () act as a force multiplie ()speedmultiplier ln each case state whecther (e) The ecnergy of an clectron is ratio 40x 10 J. 1s more Express it than in or less than 2 1 2 eV Question 2 (a) A ball of mass 0.20 kg is thrown vertically upwards with an initial velocity of 20ms Calculate the maximum potental energy1gans as t gocs up (b) For which colourof white light, is the re fractive index ofa transparent medium (0 the least, () the most of a monochromatie ay through the (c) Draw a ray diagramto show refraction sulfcrs minimum prsm when F-13 if 121 deviatic0n This paper consists of four printed pages a 12 Turn ovct (d) e) State the condition for each of the folowing () a lens has both its focal length cqual ( amy passes umdeviated through the lens What is meant by the statement 'the critical angle for diamond u 24 Questions ta Stale the range of wavelength of ultiraviolet radiations. Name one of ts sourees (6) State two ways of increasing the frequency of vibrations ofa stretchcd string 121 ()The ratio of amplitude of two waves of same pitch is 3:4 What is the ratio ot their 0) loudness? () frequencyT (d) Differentiate between heat capacity and specific beat capacty 2 (e) Towhich wre is the metallic case of an electric appliance connectodr uve erea0 Question4 (a) Grve two difference between ohmic and on-obmsc (6) What is the etlect of increase in pressure on point of water? the restance. meltmg point of ce and botling (c) The V-I graph for a series combnation and for combination of two resistors Is shown in figure. Which of two A or parallel B, represents the parallel combination? (d) Why are infra-red radiations preterred over ordinary visible light tor taking photographs in fog? (e) State oneuse and one harmful efect of radioactivity - 13 (2) SECTION U 40 marka) Ledestions (a) An electric heater inf poer 3kW s ued for 10h How much enery d conume? Espress your aweE 6) (01 joule act vertically upsiands and dowwads Two fonces cach of magnitude 2N Im which is piveoted at wo ends ofa uniform rod of lengts respectively at the torces ab0ut tne (C) its the resultant moment o1 genent and cdetermine tmid point ofa ctiort of 1000N lf system has 5 pulleys. an block and A downward dircction to rase a load of 43009N, calculate: taclkle 8 nended m 6 ) t h e mechanical advantag rati0, and ( the velocity () the efficicncy of the 14 systcm Naistion6 (a) Aray of bght is normally ncident on one Eace of an cquilateral glass prim ADiwer the following on the tust Lace of the pram What 1s the angle of mcidence (0 at the sioond lace of the prsm ( ) What will be he angle of incdlence by tbe prian ) Will the light ray sutlor s n i i a m deviation lens day light winheut a of Isit possible to burn piece paper using cunves to w a (b) using a rnatch box or any durect harne raw a ray dagram three times magnified erest and () A convex lens formsan of it F tnd n iront l0 cm placed at a distance (0the position o () the ocal the length or support your image of an obyject age lens erestion 7 (a) Gve one example cach of natural vibration, lorced vibration and resonace (b) ) Name the characteristics of sound which enables a person to differentiate between two sounds with equal loudncS but havIng ditterent trequcncies (1) Define the characteristics named by you tn 3) (1) Name the characteristic of sound which enables ot person to ditercntate between two sounds ot the same loudness and trequency but producod tY diflerent instruments (C) A boy stands 60m n front of a tall wall claps. The boy to claptbe cvery time an ecbo 1s heard. Another boy finds that the tinecontinues taken between and trst and fity-first clap is 18s. Calculate the speed of sound F-13 (3) A Turn Question 8 and same lengtti have radi t and () (Twe wires of same muteral fheir restances and their resistivities respectively Compare of a bulb. (0 Name the material used to make filament in a wire dependi when curent (b) Name the factors on which the heat produced s s e d on t, and stale fhow doc (e) The cireuit dagram shows buttery of e.m depends on the tactors stated ty y o tlhree resistors 202, 40 and R2 connected to a of 0.25A flows 2V and intermal restance 32. 1f main current theough thie circuit, find dittlercnge acros the 402 resistor h e potential the potential ditlerence acros thie ( () (W ternal resistanoe of the oell the potential ditierence acroN the R2 resistor the valuc of R Question (0) tempcnatu State three diferenoe between hent aod rate and its ice at 0Cs heated at a constant (6) 1kg of water is every 30s till formod at 90'C. time Drawa temperature represent the change of phascs. (c) A hot iron ball of mass kg 0.2 s aulded into 0.5kg of recordcd alier temperature water at graph to 10C The resulting the temperature of hof ball specific heat capact Suc Calculate hoat capacity of water42x 10kg k of iron- 336/ kg k' and specifie temperature s Question 10 ( a ) Acertain mucleus A (mass becomes a nucleus B oumber 238 and atomic number (mass 92) number 234 and atomic number yu is radioactive by the emisSOn of a particlc 0) Name the particle emitted an5wer 01) Explain how yOu antvcd your Pesction form.of a (1) Statc the change in the cach of alpha, beta and gamma State the properties al reaCD 6) radiations in terms of nature ( s (i) charge of 30 steps cach 20cm high (C) Aboy of mass 40 kg cimbed up a flight 30 does the same in mnutes Conpare munutes and a gul of mas5 Ng () the woN () the power developed by them F-13 in (g- 10ms) and 2
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