TOPPER SAMPLE PAPER 2 Class XII- Physics Time: Three Hurs Maximum Marks: 70 General Instructins (a) All questins are cmpulsry. (b) There are 30 questins in ttal. Questins 1 t 8 carry ne mark each, questins 9 t 18 carry tw marks each, questins 19 t 27 carry three marks each and questins 28 t 30 carry five marks each. (c) There is n verall chice. Hwever, an internal chice has been prvided in ne questin f tw marks, ne questin f three marks and all three questins f five marks each. Yu have t attempt nly ne f the given chices in such questins. (d) Use f calculatins is nt permitted. (e) Yu may use the fllwing physical cnstants wherever necessary. 19 e = 1.6 10 C c = 3 10 ms 8 1 34 h = 6.6 10 Js µ = 4λ 10 TmA 7 1 23 1 kb = 1.38 10 JK 23 NA = 6.023 10 / mle 27 mn = 1.6 10 kg 1. In spite f having magnitude as well as directin the current is a scalar quantity. Why? (1) 2. Give the directin in which induced current flws in the wire lp, when the magnet mves twards the lp as shwn belw.
(1) 3. Hw is the current represented mathematically in frward bias? (1) 4. What is the rati f speed f infrared rays and ultravilet rays in vacuum? (1) 5. Hw will the size f an bject appear changed when viewed by a telescpe having fcal length f the bjective and eyepiece as 60 cm and 5 cm respectively? (1) 6. Find the rati f nuclear densities f the tw nuclei having mass numbers in the rati 1 : 4? (1) 7. A. C. pwer is transmitted frm ne statin t anther at highest pssible vltage. Why? (1) 8. Why d semicnductr devices nt wrk at abslute zer temperature? (1) 9. An electric diple with diple mment 4 10 9 directin f a unifrm electric field f magnitude magnitude f the trque acting n the diple. (2) C-m is aligned at 30 with the 4 1 5 10. NC Calculate the 10. What is the change in resistance f a wire when its radius is halved and the length is reduced t ne furth f its riginal value? (2) 11. In Yung s duble slit experiment the size f slits is taken f the rder f the wavelength f the light used in the experiment. Give reasn fr it. (2) 12. Why are ferrmagnetic materials used in memry devices? (2) 13. Find the wavelength f electrmagnetic waves f frequency 6 x 10 12 Hz in free space. Give the tw applicatins f this wave. (2) 14. A cnvex lens f refractive index 1.5 has a fcal length f 18 cm in air. Calculate the change in its fcal length when it is immersed in water f refractive index f 4/3. (2) 15. The given graph shws the variatin f charge q versus ptential difference V fr capacitrs C 1 andc 2. The tw capacitrs have same plate separatin. But the plate area fc 2 is duble than that f C 1. Which f the lines in the graph crrespnd t C1 andc2 and why?
16. Explain hw the maximum kinetic energy f the electrns emitted frm a metal surface vary with the frequency f incident radiatin. (2) Draw a graph shwing the variatin f stpping ptential with frequency f incident radiatin in relatin t pht electric effect. Deduce an expressin fr the slpe f this graph using Einstein s phtelectric equatin. (2) 17. The half life f 14 6C is 5700 years. What des it mean? Tw radiactive nuclei x and y initially cntain n equal number f atms. Their half lives are 1 hur and 2 hur respectively. Calculate the rati f their rates f disintegratin after tw hurs. (2) 18. Distinguish between frequency mdulatin and amplitude mdulatin. (2) 19. S 1 and S 2 are tw hllw cncentric spheres enclsing charges Q and 2Q respectively. i. What is rati f the electric flux thrugh S 1 and S 2? ii.hw will the electric flux thrugh the sphere S 1 change, if a medium f dielectric cnstant 5 is intrduced in the space inside S 1 in place f air? (3) 20. Tw dielectric slabs f dielectric cnstants K 1 and K 2 and f equal width are filled in between the tw plates, each f area A f the parallel plate capacitr. Hw des the capacitance f the capacitr get affected? (3) 21. A pint charge +10µC is at a distance 5 cm directly abve the center f a square f side 10 cm as shwn in figure.
22. What is the magnitude f the electric flux thrugh the square? A parallel plate capacitr with air as dielectric is charged by a d. c. surce t a ptential V. Withut discnnecting the capacitr frm the surce, air is replaced by anther dielectric medium f dielectric cnstant 10. Hw des electric field between the plates and energy stred in the capacitr change? (3) 23. A ray f light which mves frm denser t rarer medium underges ttal internal reflectin. Derive the expressin fr critical angle in terms f speed f light in the respective media. (3) 24. State the cnditin under which the phenmenn f resnance ccurs in a series LCR circuit. Plt a graph shwing variatin f current with frequency f a.c. surce in a series LCR circuit. (3) 25. Tw cherent surces whse intensity rati is 81:1 prduce interference fringes. Find the rati f intensity f maxima and minima in fringe system. (3) 26. A lng slenid with 15 turns per cm has a small lp f area 2.0 cm 2 placed inside nrmal t the axis f the slenid. If the current carried by the slenid changes steadily frm 2A t 4A in 0.1 sec, what is the induced emf in the lp while the current is changing? (3) 27. Hw des the size f a nucleus depend n its mass number? Explain why the density f nuclear matter is independent f the size f nucleus. (3) 28. Give the frequency ranges f the fllwing: (i) High frequency band (HF) (ii) Ultra high frequency band (UHF) (iii) Super high frequency band (SHF) (3) 29. Using Ampere s circuital law, derive an expressin fr the magnetic field alng the axis f a tridal slenid.
Derive an expressin fr the trque n a rectangular cil f area A carrying current I placed in a magnetic field B at an angle θ t the directin f the field. (5) 30. Derive lens maker s frmula fr a duble cnvex lens. Draw a ray diagram f a cmpund micrscpe shwing the final image frmatin at least distance f distinct visin D. State its wrking principle. Shw that its magnifying pwer is given as M v D 1 1 u Fe ve = + 31. The circuit symbl f a lgic gate and tw input wavefrms A and B are shwn in the figure given belw. (5) i) name the lgic gate ii) write its truth table iii) Tabulate the details f utput wavefrm & represent its utput wavefrm graphically. With the help f a labeled circuit diagram, describe wrking principle f a cmmn emitter amplifier using a p n p transistr. Define the terms current gain and vltage gain and write their expressins. (5)