WP¥ Kllv Rrau' Dºlp]Q]¨OU. CT Yop¾v S\Lh|°¥¨V D¾qu Iuoflsjl, Oãoçvqoolp] Bwp V]J]Opu Ja¾lsjl Kla]Š
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F.Y. Reg. No. ....................................... 623623 March 2017 Name ............................................ Part - III ELECTRONICS Maximum : 60 Scores Time : 2 Hours Cool off time : 15 Minutes General Instructions to Candidates : z There is a 'Cool off time' of 15 minutes in addition to the writing time of 2 hrs. z You are neither allowed to write your answers nor to discuss anything with others during the 'cool off time'. z Use the 'cool off time' to get familiar with questions and to plan your answers. z Read the questions carefully before answering. z All questions are compulsory and only internal choice is allowed. z When you select a question, all the sub-questions must be answered from the same question itself. z Calculations, figures and graphs should be shown in the answer sheet itself. z Malayalam version of the questions is also provided. z Give equations wherever necessary. z Electronic devices except nonprogrammable calculators are not allowed in the Examination Hall. j]¡SÇw°¥: z j]¡Ç]xVa yop¾]jV kOrRo 15 o]j]ãV "WP¥ KLlV RRaU' DºLp]q]¨OU. CT yop¾V S\Lh|°¥¨V D¾qU IuOfLSjL, oãOçvqOoLp] Bwp v]j]opU ja¾LSjL kLa]Š. z D¾q°¥ IuOfOÐf]jV oOÒV S\Lh|°¥ èÈLkO¡‹U vLp]¨eU. z IŠL S\Lh|°¥¨OU D¾qU IuOfeU. z KqO S\Lh|jÒ¡ D¾qRouOfL¢ RfqR´aO¾O Wu]´L¤ Dk S\Lh|°tOU ASf S\Lh| jÒq]¤ j]ÐV fRÐ RfqR´aOS¨ºfLeV. z We¨V WPŸsOW¥, \]Nf°¥, NYLlOW¥, IÐ]v D¾qSkÕr]¤¾RÐ DºLp]q]¨eU. z Bvw|oOç òs¾V yovLW|°¥ RWLaO¨eU. z S\Lh|°¥ ospLt¾]sOU j¤W]p]ŸOºV. z SNkLNYLoOW¥ R\áLjLWL¾ WL¤¨OSsãrOW¥ Ku]RWpOç KqO CsWVSNaLe]WV DkWqevOU kq}ƒLzLt]¤ DkSpLY]¨OvL¢ kLa]sæ. K-820 1 Turn Over 623 1. Write the names of any four 1. CsWVSNaLe]WVy]Rs v|f|yVf devices used in various fields of SoXsWt]¤ DkSpLY]¨OÐ application of electronics. (2) JRfË]sOU jLsV DkWqe°tORa SkRquOfOW. (2) 2. A resistance is given with the 2. fLRu fÐ]q]¨OÐ Wt¡ SWLScLaO following colour code. WPa]p ry]ð¢yORºÐV WqOfOW. Yellow, Violet, Orange and o´, vpsãV, KLrµV, SYL¥cV. Gold. a) Af]R£ vLs|O WºOk]a]¨OW. (2) a) Find its value. (2) b) CT ry]ð¢y]Rs vLs|O oLrL¢ b) What is the range in which yLi|fpOtt kq]i] INf? (2) its resistance varies? (2) 3. a) Discuss the difference 3. a) RIc]p¤ SvL¥SŸ^V SyLuVyOU between ideal and practical NkLWVa]¨¤ SvL¥SŸ^V SyLuVyOU voltage sources. (2) fÚ]sOtt v|f|Ly°¥ IuOfOW. (2) b) The internal resistance of an b) KqO RIc]p¤ SvL¥SŸ^V ideal voltage source is ......... SyLuVy]R£ CS£e¤ i) 0 ry]ð¢yV .................... BeV. ii) ∞ i) 0 iii) 1Ω ii) ∞ iii) 1Ω iv) 1000 Ω (1) iv) 1000 Ω (1) 4. A sine wave is represented by 4. KqO RRy¢ Svv]Rj the equation υ =×+5Sin() 628 1030 t 30 IÐ 30 υ =×+5Sin() 628 10 t 30 . Find yovLW|U RWLºV Nkf]j]i}Wq]\ÿ] the peak voltage, r.m.s. voltage, q]¨OÐO. Cf]R£ k}¨V SvL¥SŸ^V, time period and phase of this r.m.s SvL¥SŸ^V, RRaU k}q]pcV, signal. (4) SlyV IÐ]v WºOk]a]¨OW. (4) K-820 2 623 5. The concept of energy band is 5. Ij¡^] mL¢cV IÐ BwpU used to classify materials. DkSpLY]\ÿV Roã}q]psOWRt fqU a) What is the bandgap energy f]q]¨LU? of insulators? (1) a) C¢yOSsã¡y]R£ mL¢cV Y|LkV b) Draw the energy band Ij¡^] INf? (1) diagram of metals. (1) b) Roã¤y]R£ Ij¡^] mL¢cV c) Free electrons are found in cpNYU vq¨OW. (1) .......... band. (1) c) Nl} CsWVSNaLeOW¥............. mL¢c]¤ WLeRÕaOÐO. (1) 6. Give the names of two p-type 6. qºV k]&RRaÕV ScLÕ£OWtORa dopants. (1) SkRquOfOW. (1) 7. When a PN junction is forward 7. KqO PN ^UYVx¢ SlL¡SvcV mpyV biased, the barrier potential R\pVfL¤ INf SvL¥SŸ^]¤ Wr£V decides the voltage at which WºWVaV R\áeRoÐV junction conducts. f}qOoLj]¨OÐfV mLq]p¡ RkLŸ¢x|¤ BeV. a) Write the values of barrier a) y]s]¨¦, R^¡SÚj]pU potential for silicon and cSpLcOWtORa mLq]p¡ germanium diodes. (1) RkLŸ¢x|¤ INf? (1) b) What is the barrier potential b) KqO RIc]p¤ cSpLc]R£ of an ideal diode? (1) mLq]p¡ RkLŸ¢x|¤ INf? (1) 8. In the following circuit, find the 8. fLRu RWLaO¾]q]¨OÐ y¡¨|PŸ]¤ voltage drop accross the resistor R IÐ Rry]ðr]Rs SvL¥SŸ^V R. (2) SNcLÕV WºOk]a]¨OW. (2) K-820 3 Turn Over 623 9. Draw the forward and reverse 9. KqO RIc]p¤ cSpLc]R£ characteristic of an ideal diode. (2) SlL¡SvcV, r]SvuVyV W|LqWVar]ð]¨OW¥ vq¨OW. (2) 10. A transistor is a special 10. CsWVSNaLe]WVy]Rs v]v]i electronic component used in Bvw|°¥¨Lp] NaL¢y]ð¡ various applications. DkSpLY]¨OÐO. a) Name the three regions of a a) KqO NaL¢y]ðr]R£ oPÐV transistor. (1) nLY°¥ Jv? (1) b) b) Which region is doped JãvOU WPaOfsLp] ScLÕV maximum? (1) R\áRÕŸ nLYU JfV? (1) c) JãvOU vsOÕU WPa]p nLYU c) Which region is largest in JfV? (1) size? (1) d) NaL¢y]ðr]R£ qºV d) Write two applications of a DkSpLY°¥ IuOfOW. (1) transistor. (1) 11. Among the three configurations 11. NaL¢y]ðr]R£ oPÐV of a transistor. CE configuration SWL¦l]YSrxjOWt]¤ v\ÿV, CE is preferred for amplification. SWL¦l]YSrxjLeV BUkæ]l]S¨& Why? (2) xjO Svº] DkSpLY]¨OÐfV. IÍV RWLºV? (2) 12. Draw the symbols of the 12. fLRu RWLaO¾]ŸOttvpORa y]Um¤ following components. vq¨OW. a) NPN transistor a) NPN transistor b) FET b) FET c) LDR c) LDR d) SCR (2) d) SCR (2) K-820 4 623 13. Match the following. (2) 13. S\qOUka] S\¡¨OW. (2) Device Application DkWqeU DkSpLYU TRIAC Light Detection TRIAC RRsãV c]ãWVx¢ LDR Temperature measuring LDR fLkU At¨¤ LED Motor speed control LED SoLSŸL¡ yVk}cV W¦SNaL¥ Thermistor Electricity to light Rf¡o]ð¡ CsWVNa]y]ã]Rp RRsãL¨] conversion oL㤠14. A rectifier circuit is used to 14. AC Rp DC pL¨OÐf]jLp] convert AC to DC. RrWVa]lp¡ y¡W|PŸV a) Which component is the DkSpLY]¨OÐO. main part of a rectifier? (1) a) RrWVa]lpr]Rs NkiLjRÕŸ WSÒLe£V JfLeV? (1) b) Why a step down b) transformer is used in KqO RrWVa]lpr]¤ RðÕV cT¦ rectifier circuits? (2) NaL¢yVSlL¡o¡ DkSpLY]¨O ÐfV IÍ]jV? (2) c) A large value capacitor is c) RrWVa]lpr]R£ KTŸVkOŸ]¤ connected at the output of a vs]p vLs|P Dtt WÕLy]ã¡ rectifier. Why? (2) WeWVaV R\áOÐRfÍ]jV? (2) 15. The maximum efficiency of a full 15. KqO lO¥SvvV RrWVa]lpr]R£ wave rectifier is ........... JãvOU WPa]p Il]x|¢y] ............... BeV. a) 40.6% a) 40.6% b) 81.2% b) 81.2% c) 50% c) 50% d) 100% (1) d) 100% (1) K-820 5 Turn Over 623 16. Amplifier is used to increase the 16. KqO y]YVjs]R£ AtvV signal level to a desired value. AjOSpL^|oLp vLs|Ov]Ss¨V Dp¡¾OÐf]jLeV BUkæ]lp¡ a) Define the gain of an DkSpLY]¨OÐfV. amplifier. (1) a) KqO BUkæ]lpr]R£ RYp]¢ (1) b) A signal 2100Sinπ t is given IÐL¤ IÍV? to the input of an amplifier b) RYp]¤ 50 Dtt KqO with gain 50. Write the BUkæ]lpr]R£ C¢kOŸ]¤ 2100Sinπ t IÐ y]YVj¤ equation of the output signal. (2) RWLaO¾L¤ KTŸVkOŸ]¤ W]ŸOÐ c) If two amplifiers of gain 30 y]YVjs]R£ yovLW|U IÍV? (2) and 20 are cascaded, what is c) 30, 20 IÐ]°Rj RYp]jOtt the overall gain? (1) qºV BUkæ]lprOW¥ S\¡¾O v\ÿL¤ BRW RYp]¢ INf? (1) 17. Which component in the 17. KqO BUkæ]lp¡ y¡¨|PŸ]¤ Rf¡o¤ amplifier circuit prevents r¦ISv fapOÐ WSÒLe£V JfV? thermal runaway? a) CE b) CC a) CE b) CC c) R d) R (1) (1) E C c) RE d) RC 18. Oscillator circuits are used to 18. NaL¢yVo]ãrOWt]¤ WLq]p¡ y]YVj¤ generate carrier signals in DºL¨OÐf]jLp] KLy]Ssã¡ transmitters. DkSpLY]¨LrOºV. a) Give two examples for a) KLy]Ssã¡ DkSpLYRÕaO¾OÐ transmitters where NaL¢yVo]ãrOW¥¨V qºV oscillators are used. (1) DhLzqeRouOfOW. (1) b) Draw the waveforms of b) cLÒVcV, A¦cLÒVcV damped and undamped KLy]Ssx¢y]R£ SvvVSlLUyV oscillations. (2) vq¨OW. (2) c) What is the reason for c) cLÒVcV KLy]Ssx¢ damped oscillations? (1) DºLWOÐf]R£ WLqeRoÍV? (1) K-820 6 623 19. An oscillator uses ......... feedback. (1) 19. KqO KLy]Ssã¡ ................ l}cVmL¨V DkSpLY]¨OÐO. (1) 20. For an oscillator, phase shift 20. KqO KLy]Ssãr]R£ sPÕ]R£ BRW around the loop is ............ SlyV x]lVaV ............... BeV. a) 900 a) 900 0 b) 180 b) 1800 c) 3600 c) 3600 d) 2700 (1) d) 2700 (1) 21. Every number system has a 21. IsæL jÒ¡ y]𰥨OU KqO SmyV particular base. DºLp]q]¨OU. a) What is the base of a) RzWVyLRcy]o¤ jÒ¡ hexadecimal number system? (1) y]ð¾]R£ SmyV INf? (1) b) Find the decimal value of b) (231)4 IÐ jÒr]R£ Rcy]o¤ (231)4. (2) vLs|O INf? (2) (Hint : Assume there is a number system with base 4) (yP\j : 4 SmyOtt jÒ¡ y]ðU DRºÐV WqOfOW.) 22.