Page 1 :
Ne eageee eee eee y GU ECE OCCUTUAT, , oe ea, (3 Education Board, Gandhinagar., First Exam October — 2021, , Date : 20/10/2021, , , , , , Std: 12, Subject : Physies (054) Day : Wednesday, Total Marks : 100 Time : 3 Hours, {, PART:A Bae, Time : | Hours | | Maximum marks : 50, ©, Instructions a6, (1) There are 50 objective type (M.C.Q.) questions in Part : A and all questions, are compulsory. a, (2) The questions are serially numbered from 1 to 50 and each carries | mark. Ww ¢, (3) Read each question carefully, select proper alternative and answer in the ¢, O.MLR. sheet., (4) The OMR sheet is given for answering the questions. The answer of each, question is represented by (A) O, (B) O, (C) O, (D) O. Darken the circle @of 4, the correct answer with ball-pen. J L, (5) Students may use a Calculator and log-table, if necessary. mM, _, rr, 1. The dimensional formula of electric Max is ..........+++++, A (AMET A" (B) M?7LT At soot 3q-t opt aye |, 2. An electric dipole with dipole moment 4 x 107 Cm is aligned at 45° with the direction of m, uniform electric filed of magnitude 5 x 10¢ NC'. The magnitude of the torque acting on y, the dipole is ......+.-0+++ “OS bsete |, > 2 x 10445 (B) 104 Nm (C) Zero (D) 2V3~ 10° J, C/ \Figure shows tracks of four charged particles in a uniform electric filed. Which particle, _- has the zero charge to mass ratio ? gv, ws ++ + +e + t+ + t+ =, (2, , , , , , , , AL, (B)2 ( (D) 4 iz, Mees The number of an electron in - 1 C charge isSpproximately ..., (D) 107° ., , \ = (ay0” (B) 6.25 * 10"° (C6 10", @ The electric filed at the midpoint of the line joining the two point charges 3 »C and, , = 3.pC located at 20 cm IS+..--r+ese0e00 nc!, (A) Zero (B) 36 «10° (C) 0.18 x 10° (D) 5.4 x 10°, 6. A proton falls through a distance of 3.5 cm in a uniform electric filed of magnitude, , 2.104 NG, The acceleration of proton Is ......» ms”, (Mass of proton is 1.6 x 107” kg), (By 2410" (C) 1.75 x10" seal) 0.628 x10", , etsy, oh xbxto, C 4, ma aw atte’ Ki jth Tre
Page 2 :
tric dipole one 1's axis at distance ry (14 >> 4) any, , sity duc sectrie, é spetrjenl Med intensity due fo ane, j an so gHNG, CHEN ys hy S eeeeeeeeeees, i is . > an) are same, yer, one atorial at distance 12 (rz e, oe a 2 (B) 1: V2 (Cc) v2 V2:1 (D) vi, (A) I: ates are parallel and close to each other. On their inner faces, , i 1, , Two large, thin metal p ‘, ame signs and of magnitude 26.7 x 10° 2, , i the plates have surface charge densities of s# mi ang, n the outer region of the second plate is... £ = 8.9 x 10 sai), , The electric (iled i, seys x 10 Nc (D) 4 x10" NC!, , (B)2 x10" Nc!, , ”, i ‘an js in the direction (with stistanee) in which the potential decreases steepest., 2 . A 5 electri filed (B) Electrostatic potential @ F, 2% w) Electric flux : , (D) Electric potential energy ., Seay hich of the following is dimensional less ? . vate “e, or a Permittivity of medium ‘dielectric constant ve Vv, (D) Capacitance C, , a" (C) polarization, following units ? 2 Fes, , ee is not the unit of capacitance among the, \ : ; 1 :, ; (aycv" (B) Cc (NC 'm) (c)C?N'm" (Dens - cf), , (4 A Spherical conducting shell of inner radius r; and outer radius r, has a charge Q. !, pe charge qvis placed at the centre of the shell. What is the surface charge density on thi, , inner surface of the shell ?, , , , , , Q a 4 . Q. Q +q, “4 (A) mri _@ ar? ( any (D) 4nr}, 13. The electric dipole potential falls of at large distance as ........+++, (Ayr? : _®) re, (Ors ) does not depend on distance, Led 474 electron is accelerated by a potential difference of 1 V; then it would gain energy, os 4° eee see de, yioe yle (A) 9.1 viv! (B) 0.175 x10!” (C) 1.6 x10"? (D) 5.68 x107!?”, 15. Pe capacitance of .a condenser jis 4 x 10° F and its potential is 100. V. The ener,, a. plo teleased, on: discharging it fully will be .......2....006 : ; &, N (A) 0.04 J (B)9.02 J (C) 0.025 J (D) 0.05 J, 16. C, =C, C, =2C, C3= 3C and Cy=4 C then the equivalent capacitance between the, , point A and Bis ........seeseeeeeeee Cc.
Page 3 :
ry se be e a. vy tow, 13) If th ie \4 ¢ Yo s /, mae four colors on the resist ‘ Ro SB w, ‘ Fesistance is oo... sistance are orange, blue, yellow and gold then the value of, (A) 360 +5 %) KO . gm, (C) 3600 + 10%) ka (B) (3.645%) kQ ' :, , ie (D) (0.36 + 10 %) 2, nsity in copper wire is 2 x 10° Am, the diameter of wire, , 19 The Current de, , is 6.28 A then, "If the current passing from the wire, , , , , , , , , (A) 10 m ao8 p= Axle, (By10% m (C)2« 104 4 € a, 0, 20. The storage battery ee has an emf of Oe ae i San a vu is 0.4 Q. What is the maxi - If the internal resistance of the battery G2 Or., wre _ aximum current that can be drawn from the battery ? —h, 21 In a potenti t Bea ee dale :, Ss 7 tenet if fie ei er ar rangement, a cell of emf 1.25 V gives a balance point at 35 cm cy, on Vf 2 Wire, A the cell is replaced by another cell and the balance point shifts to G., _ Ze cm, then the emf of the second cell is .. ny. axle, a 2.25 (B) 0.7 (C) 12.26 (D) 1.25 ax :, cov Given n resistors each of resistance R. What is the ratio of the maximum to minimum f Oo, q resistance ? y ‘i, Ze Pi aye, 4X) (Ayn (Bryer Cn )1, . ; Byn'y (©) (), 23. In a wheatstone briagé shown in figure, the equivalent resistant between two ends of, battery is ............ Q, ie, Be a, Ie Lakhs Bare ay, 2 BlLiv — Ayan, Leet Oe E, cayyNBhe, 7 QI. &, fas pee, . ‘2. ‘ CO s Le Jb,, So Qi L Joh, n Vv " : + (, a i. R R 5, (A) 2R a eo Oz O75 a, 24, .>-5 cells each of emf 2 V “and internal resistance 0.02 are joined in series with resistance 10, 5 ae of 6.5 Qthen the current drawn in the circuit is ..........+.. : ee, (A) 1414 | (B)J.51 A (C) 0.25 A Oe 6., , , , , , , , , , , , , , , , A steady current flows in a metallic conductor of non-uniform cross-section. Which of, these quantities is constant along the conductor ? ; ; g l =, , Ay Current density a field a (©.Current (D) drift speed j, A Straight wire of mass 0.3 kg and length 1.5 m carries a current of 4 aS To Suspended, — |, it'in a mid-air required magnitude of uniform horizontal magnetic field is .........+.++ T:, , : ee Nh, ‘ (g =10 ms?) : { YE= (, (A) 0.5 (B) 11.5 (C) 200 (D) 0.66 vz (0!, , ti parallel currents is .....++-se+++sesreseeee+, , ‘The electric force between an, , i elect (B) zero. LR \o, (G) attrac Isi d attractive, , (C) att itive (D) repulsive and attr: 2, , gth of a solenoid is 1000, and it ‘carries a current 5 A. ic filed inside the solenoid ?, , imber of turns per unit len, (©) 9.42 x10° T (D) 6.28. 10° T ., , the magnitude of the of the magnet, yO? TB) 3:14 x 10° T
Page 4 :
1» : ", 5. Vhe Stanit of magnetic Moment is oe. hess, (D) TmAt, , A yor (B) Am (C) Am?, 30. Whieh of the following is proper formula of Lorentz force ?, , \ i ' ; 2 (RXV, (Yea [ui (vx B)| (B) F=4 [E- (Bx ¥)|, , (wy F =a [B+ * v)|, , , , {~ (Cy q \v + (B xv)|, (a 1f the number of turns in the galvanometer coil is increase, then its secre, (A) Current sensitivity is increase . i GN", gp Kh © =, , , , (B) Voltage sensitivity is increase “et 30, Both current and voltage sensitivity are increase. U4, , (D) Current and voltage sensitivity doesn’t charge: a., 2, If the speed of charged particle moving through a magnetic file, ~ radius of curvature of its trajectory will «s.-0000800"*"* erst . |, (A) decrease (B) ne half (C) not change Pe incre, 33. A charged particle so ee, 5 (B) magnetic fi, , J p (A) electric filed s, (D) none of the : _, ath of radius in a plane inside, , 3 fe (C) both these fileds, , , i r ves on a circular P, 34. particle of charge 4 and mass m moves ona circula ven eae, “and normal to a uniform magnetic filed B. The number of revolution y the, , / _ particle in unit time iS .--.-+eeefrr 7" ™ anq?B, (D) Tin, , dis increased then the, , a, nN, , , , led, , gain energy du tO -+++07", se fields, , , , - 2am 2nqB, be wT ia, te in horizontal plane will,, , 35.; At magnetic pole, a magnetic needle allowed to rota a, Stay in north — south direction only (B) stay any position” , (C) stay in east — west direction only (D) become rigid showing no movement, , a, B 36. ZA short bar magnet of 0.4 Am’ magnetic moment, placed in an external magnetic field of, 800 G. What is the work done in moving it from its most stable t, , YD 6B position ?, : 30.032 J (C) 0.064 J (D) Zero, , aK 0.16 J, vn What is the magnitude of the equatorial field due to a bar magnet of length 5 cm ata, distance of 50 cm from its mid-point ? the magnetic moment of bar magnet = 0.4 Am’., , teat te s07T oe x107 T (64x 10ST ’ — (D)0.32 x10" T, , In the magnetic meridian of a certain place, ‘the horizontal component of the earth’s, magnetic field is 0.26 G and the dip angle is 60°. The magnetic field of the earth at this, , o most unstable, , , , , , location is ...--+-+-+++ 2% Ger, ) 0.26 (B) 0.13 (C) 0.72 Dyn., fi A Solenoid carry a current of 3 A. If the number of turns is 1000 ot, i magnetic intensity H =......---++ l pe Meee neu =, Basar (A) 2 x 10° A/m (B)3 «10° A/m (90.03 x10"! A/ hg, sy @r Which of the following is diamagnetic substance 2 es (oy zene, = ) aluminium (B) nickel ( ‘i, % & : C) bis :, 41. In a permanent magnetic at room temperature, ; muth (D) calcium, = 4 oy oe moment of each ntolecule is zero,, 7; 5 ) the individual molecules have non-zer, vs i “zero ma ic, : : aligned. magnetic moment which are al, : all perfectly, 6 ‘ aS : (©) domains are partially aligned. :, oc: hot om: (D) domains are all perfectly aligned, aN e@aYiteval ro \ ee eS
Page 5 :
ee oy a mt, arnannetic’ Si . Alo ge oe :, 42. A Paramagnetic sample shows a net'magnetisation of 8 Am! when placed in a external \, a magnetic filed of 0.6 T at a temperature of 4 K, when the same sample is placed in a, external magnetic filed of 0.2 T at a temperature of 16 K, the magnetisation will, , DC vecceceseseeceeeeeeeeeeese me xo. 2, (A) = Am! (B) 5 Am" (6 Am" (0) 2.4 Am!, 43. The dimensions of mutual inductance is .......- § easscessse, (A)ML?T7 A BTML? T7A* (C)ML?T3 a7 (D) ML2T3.2, 44. Which of the following is not useful to get a deflection in a galvanometer connected with, a coil.?, ut a rod of soft iron inside the coil. 2 Je, (B) Hold it steady near the second coil with a steady flow, (C) Moving the magnet relative to the coil. aw, (D) Accelerating the coil in an irregular magnetic filed. ty, , 45. A wheel 10 metallic spokes each 1 m long is rotated with a angular speed 47 rads! ina, , on plane normal to the horizontal component of earth’s magnetic filed Hy at a point. If ¢, Hy =0.4 x 107 T then the induced emf between the axle and the rim of the wheel, , TS ccceeececceeees ANG +t u, (42.512 x104 V (B) 6.28 x107 V, (C) 3.14 x107 V (D) 12.56 x107 V = t Bw, , ps, , , , 46. Faraday’s law of induction gives ...----++++ a, a (A) ofily magnitude of emf (B) only direction of emf ako:, (C) both magnitude and direction of emf (D) rms value of emf a, 47. In the AC generator if the angular speed of armature.is doubled the maximum induced, emf Will De ....eeeeeeereeestrertet, (A) of the fourth (B) half (C) four times ue ae, kamla peddles a stationary bicycle the pedals of the bicycle are attached to a 100 turn ¢, , 48, Vo of area 0.1 m?. The coil rotates one revolution per second and it is placed ina, uniform magnetic filed of 0.01 T. perpendicular to the axis of rotation of the coil, then, , the maximum voltage generated in the CON iS .... cece eee eee eee ees, , (A) 0.314 V ee Vv (C) 0.157 V (D) 1.256 V, oom in a falls. from 5.0 A to 0.0 A in 0.1 s. If an average emf of 200 V induced, then, , the self inductance of the circuit is ........++++++- H. ,, , (A) 5 (B) 10 OA (D) 0.5, , The distance between two extreme points of The two wings of an aeroplane is 50.m. It is, , 50., !, Vo flying at a speed of 360 km hb’ in horizontal direction. If the vertical component of, i earth’s magnetic filed at that place is 2 x 107 Wbm*, the induced emf between these two, , end points is ..., (A) 0.1, , , , 1.0 (C) 0.2 (D) 0.01, , L, po *Snes on YSOu AR”
