pre test paper xii - 2

8/12/2019 Pre Test Paper XII - 2

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12. 4ie epression for resoling power of a co#pound #icroscope. =ow will the resolingpower change if(a) red light is replaced by blue light"(b) dia#eter of ob9ectie is increased"

1$. A lens for#s an i#age of an ob9ect. %he ob9ect distance is u and the i#age distance is .%he gien graph shows ariation of u with .

(i) What is the nature of the lens& ob9ect and i#age"(ii) What is the focal length of lens"

1/. >n the diagra#& ?@ is a surface with radius of curature 13 c#. B is a point ob9ectplaced 2+ c# fro# the pole of the surface ?@. Bbtain the position of the i#ager of B.

4ien (water) C4

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13. What is s!y wae propagation" Ber what frequency range does it wor!" Why this #odeis not suitable for %: trans#ission.

+,

Draw a bloc! diagra# of radio receier. 'riefly discuss the function of different parts ofthe sa#e.

15. Bbtain binding energy per nucleon for a carbon nucleus 512 ta!ing #ass of carbonnucleus to be 12.+++++ u.

17. With the help of a neat circuit diagra#& describe how can we co#pare the e#fs of two

gien pri#ary cells. State two #ethods by which a potentio#eter can be #ade #oresensitie.

1,. A current carrying loop behaes as a #agnetic dipole. Write epression for its #agneticdipole #o#ent. 4ie its S> unit. State the rule to find the direction of the #agnetic dipole#o#ent.

A circular current carrying loop when placed in a unifor# #agnetic field of intensity 'eperiences a torque of #agnitude . %he loop is opened and rewound into one haingdouble the nu#ber of turns and placed in the sa#e field with sa#e orientation as thegien loop. alculate the #agnitude of the torque eperienced by this new loop.

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Define the three ele#ents of earths #agnetic field. Which of these ele#ents is (a)Eai#u#& (b) Eini#u# on equator and on poles"

10. >n the gien figure a light bulb and a capacitor are 9oined with an ac source through aswitch as shown. %he la#p glows with a certain brightness. =ow will the brightnesschange if

(i) the frequency of ac source is increased"(ii) a dielectric slab is introduced between the plates of the capacitor"

2+. ou are gien three lenses F1& F2and F$each of focal length 2+ c#. An ob9ect is !ept at/+ c# in front of F1as shown. %he final real i#age is for#ed at the focus > of F$. Gindthe separations between F1& F2and F$.

21. Fight of waelength 3+++H falls on a plane refracting surface. What are the waelengthand frequency of reflected light"Gor what angle will (a) reflected ray (b) refracted ray beco#e perpendicular to the

reflected ray" 4ien 4

3 = .

What change if any will be obsered in nature of(i) reflected light (ii) refracted light will you obsere for light incident at the anglecalculated aboe"

22. What is an antenna" a#e two different types of antenna. 4ie one li#itation of each of

the two types. alculate the #ini#u# length of dipole antenna for a carrier wae offrequency 1.2 * 1+0=I.

2$. Jplain with the help of a diagra#& how(i) depletion layer (ii) potential barrieris for#ed in a pn 9unction diode. What happens to the width of depletion layer when the

9unction is reerse biased" What is a Iener diode" Jplain how it differs fro# a pn9unction in fabrication& characteristics and use.

2/. ou are gien a nu#ber of AD gates. With the help of a diagra#& describe how canyou use the gien gate or a co#bination of gates to realiIe (i) B% gate (ii) B6 gate.

23. Ksing 'ohrs #odel& calculate the speed of the electron in a hydrogen ato# in the n C 1and 2 leels. Also calculate the !inetic energy of the electron in each of the two leels.

25. 6ahul and 6a9at were perfor#ing an eperi#ent to co#pare the e#fs of two cells usinga potentio#eter. After co#pleting the circuit they got the deflection in the galano#eter inthe sa#e direction. >n order to hurriedly co#plete the eperi#ent& 6ahul suggested thatthey will copy and use the obserations of the students of other group. 6a9at howeer didnot agree. =e approached the teacher for help. %he teacher told the# two possiblecauses of the sa#e sided deflection. 6a9at and 6ahul rectified the circuit and co#pletedeperi#ent.(i) Fist the two causes for sa#e sided deflection.(ii) What are the alues which 6a9at possesses as a student"

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27. (a) %he following data was obtained for the dependence of the #agnitude of electricfield& with distance& fro# a reference point B& with a charge distribution in theshaded region.ied oint A ' A ' Ma/nit*de o ee&tri& ied J J-, J-27 J-2 J-15 J-3/(i) >dentify the charge distribution and f the potential due to this charge distribution& has a alue : at the point A& whatis its alue at the point '& '& "

(b) Bbtain an epression for the capacitance of a parallel plate capacitor.+,

Jplain the principle of a deice that can build up high oltages of the order of a few#illion olts.Draw a sche#atic diagra# and eplain the wor!ing of this deice. >s there any restrictionon the upper li#it of the high oltages set up in this #achine" Jplain.

2,. What are eddy currents" State the rule which gies the direction of eddy current. 4ietwo de#erits of eddy currents. =ow are these currents used in

(i) Jlectro#agnetic bra!es" (ii) Ea!ing dead beat galano#eter"+,Describe Garadays eperi#ents which led to the discoery of pheno#enon ofelectro#agnetic induction. State the laws goerning the pheno#enon of electro#agneticinduction. Jpress the laws #athe#atically. Fist three #ethods by which #agnetic flucan be aried to produced induced current"

20. Define the ter#s(i) relatie #agnetic per#eability(ii) coerciity(iii) retentiitya#e the #aterials (one in each case) which are suitable for #a!ing (a) per#anent

#agnet (b) core of electric transfor#ers. What is the essential difference between thehysteresis loops of the two #aterials" 4ie reason for your choice.

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State the principle of wor!ing of a #oing coil galano#eter. Ksing a neat and labelleddiagra#& describe its wor!ing. =ow can its current sensitiity be increased" Show thatincrease in current sensitiity #ay not essentially increase oltage sensitiity.

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pre test paper xii - 2

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