ELECTROMAGNETIC INDUCTION PREVIOUS EAMCET BITS

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Justina Nicholson
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1 P P Methd EECTOMAGNETIC INDUCTION PEVIOUS EAMCET BITS [ENGINEEING PAPE]. A cnduct d f length tates with angula speed ω in a unifm magnetic field f inductin B which is pependicula t its mtin. The induced e.m.f develped between the tw ends f the d is [EAMCET E] B ω B ω ) Ans: Sl. Its Methd : de = Bvdx = Bω xdx Bω E = Bωdx = Bω xdx = nd : Induced emf e ( BA) B ω B ω = = ( π ) d BA B = = = π ω B ω ) B ω. If a change in cuent f. A in ne cil pduces a change in magnetic flux f in the the cil, then the mutual inductance f the tw cils in Henies is [EAMCET E] ).5 ) 3 Sl. Fm laws f electmagnetic inductin dφ di = E = M M = =. 3. A cil has, tuns and 5 cm as its aea. The plane f the cil is placed at ight angles t a magnetic inductin field f 5 web/m. The cil is tated thugh 8 in. secnds. The aveage emf induced in the cil, in milli vlts, is: [EAMCET 3 E] 5 ) 5 ) Ans: dφ φ φ NAB Sl. Induced emf = = = = mv t t. Tw ins having masses in the ati : and chages : ae pjected int unifm magnetic field pependicula t the field with speeds in the ati : 3. The ati f the adii f cicula paths alng which the tw paticles mve is: [EAM CET 3 E] : 3 ) : 3 3 : ) :

2 Electmagnetic Inductin Ans: Sl. Magnetic fce = Centipetal fce mv Bq v = v q = = = v q 3 3 : = :3 5. Magnetic inductin at the cente f a cicula lp f aea π squae mete is. tesla. The magnetic mment f the lp is : ( = pemeability f ai) [EAMCET E].π.π.3π.π ) ) Ans: ni Sl. Magnetic inductin at the cente f cicula lp B =. [whee is the adius f lp] A = π π = π = Magnetic mment f the lp BA (.) π M= nia= = 6. A wie f length l is bent in t a cicula cil f ne tun f adius. Anthe wie f the same mateial and same aea f css sectin and same length is bent in t a cicula cil f tw tuns f adius. When the same cuent flws thugh the tw cils, the ati f magnetic inductin at the centes f the tw cils is : [EAMCET E] : ) : : ) 3 : ni n Sl. Magnetic inductin at the cente f a cicula cil B =. Bα B n ( /) = = = B n B :B = : 7. An inductance H is cnnected in seies with an A.C suce f V and 5Hz. The inductive eactance (in hms) is [EAMCET 5 E] π ) 5π π ) π Sl. Inductive eactance X = ω= π n = π 5 = π 8. Tw paallel ails f a ailway tack insulated fm each the and with the gund ae cnnected t a millivltmete. The distance between the ails is ne mete. A tain is taveling with a velcity f 7 kmph alng the tack. The eading f the millivltmete ( in m V ) is : ( Vetical cmpnent f 5 the eath s magnetic inductin is T ) [EAMCET 5 E] ( ().7 (. ().

3 Sl. Induced emf = Blv = Electmagnetic Inductin = = 3. V. mv 9. A ectangula lp f length f and beah b is placed at a distance f x fm an infinitely lng wie caying cuent i such that the diectin f cuent is paallel t beah. If the lp mves away fm the cuent wie in a diectin pependicula t it with a velcity v, the magnitude f the e.m.f. in the lp is : ( pemeability f fee space) (EAMCET 6 E) miv l+ b miv b ilbv ilbv x + l ) lg ) lg π x b π x l π x ( l+ x) π x Sl. Net emf = ebb ebb Net emf = Bbv Bbv = bv[ B B] i i bv i = bv = πx π ( + x) π x + x ibv + x x ibv = = π x ( + x) πx( + x) Hence ( is the cect chice.. A small squae lp f wie f side l is placed inside a lage squae lp f side (>>l). If the lps ae cplana and thei centes cincide, the mutual inductin f the system is diectly pptinal t : (EAMCET 6 E) ) l l ) l l Ans: i Sl. Magnetic inductin at the cente = B = [ sinα + sin β ] π i B = + π Flux linked with the smalle lp i. φ = Mi = BA = B = π M Hence () is the cect chice.. Tw cncentic cils f tuns each ae placed in the same plane. Thei adii ae cm and cm and cay. and.3 amp. cuent espectively in ppsite diectins. The magnetic inductin (in Tesla) at the cente is [EAMCET 8 E] 3

4 φbb t then 3 ) 5 7 ) 9 Ans: Sl. The esultant magnetic inductin at the cente is B = BBB- BBB in in B= B B = 5..3 =.5 5 = 5 =. MEDICA Electmagnetic Inductin. If the flux f magnetic inductin thugh a cil f esistance and having N tuns changes fm φbb the magnitude f the chage that passes thugh this cil is [EAMCET M] φ φ ) N ( φ φ ) φ φ N ) N φ φ Ndφ Sl. E = N( φ φ N( φ φ i = i t = t Whee i t is the chage that passes thugh the cil 3. Tw cils have self-inductance = mh and = mh espectively. The cuents in the tw cils ae inceased at the same ate. At a cetain instant f time bth cils ae given the same pwe. If I and I ae the cuents in the tw cils, at that instant f time espectively, then the value f (I /I ) is: [3 MED] /8 ) / / ) Ans: di Sl.. E = is the self inductance P= EI, P = P [ since pwe is same] di di I I = I I di di I = I I = = I. The electic cuent in a cicula cil f tw tuns pduced a magnetic inductin f. T at its cente. The cil is unwund and is ewund int a cicula cil f fu tuns. The magnetic inductin at the cente f the cil nw is, in tesla, (if same cuent flws in the cil): [3 MED]

5 =. )..6 ).8 Ans: ni Sl. Magnetic inductin at the cente f cil B = B n = B n. / = = B Electmagnetic Inductin BBB.8 T 5. Tw ins having equal masses, but chages in the ati : ae pjected pependicula t a unifm magnetic field with speeds in the ati : 3. The ati f the adii f the cicula paths alng which the tw ins mve is [EAMCET 3 MED] : 3 ) : 3 3 : ) : Ans: Sl. Centipetal fce = Magnetic fce mv Bq v = v q = = = v q 3 3 : = :3 6. A magnetic flux f 5 mic-webes passing thugh a tuns cil is evesed in 3 secnds. The aveage emf induced in the cil in vlts, is : [EAMCET M].5 ) ). Ans: dφ Sl. Induced emf in the cil = E = N 6 φ 5 E = N = t 3 = vlts 7. A cuent caying cicula cil, suspended feely in a unifm extenal magnetic field ients t a psitin f stable equilibium. In this state [EAMCET 5 M] The plane f the cil is nmal t the extenal magnetic field ) The plane f the cil is paallel t the extenal magnetic field Flux thugh the cil is minimum ) Tque n the cil is maximum Ans: Sl. In the stable equilibium the plane f the cil is nmal t the extenal magnetic field. 8. A ptn is pjected with a velcity 7 ms, at ight angles t a unifm magnetic field f inductin mt. The time (in secnds) taken by the ptn t tavese 9 ac is (Mass f ptn =.65 7 kg and chage f ptn =.6 9 C) [EAMCET 5 M].8 7 ) )

6 Electmagnetic Inductin Ans: mv Bq Sl. Centipetal fce = magnetic fce = Bqv V = m π But V = w and T = w πm Cycltn time peid T = qb Time equied t cmplete a sect f angle 9 is 7 T πm π.6 7 = = = qb.6. A cil f tuns and mean aea f 5 cm is held pependicula t a unifm magnetic field f inductin T. The esistance f the cil is hms. When the cil is tated thugh 8 in the magnetic field in. secnds the aveage electic cuent (in ma) induced is : (EAMCET 6 M) ) 36 ) 8 Ans: dφ BAN Sl. Fm e= N = t φ φ e BAN e= N ; i = = t t ( )( 5 )( =. = 3 Hence () is the cect chice.. The e.m.f. induced in a secnday cil is V when the cuent beaks in the pimay cil. The mutual inductance is 5H and the cuent eaches t ze in sec in the pimay. The maximum cuent in the pimay befe it beaks is (EAMCET 7 M).A ).A.6A ).8A Ans: Sl. MdiP es = ( I ) p = 5 5 =. ; Hence () is the cect chice. I p. A cil f H inductance is cnnected in seies with a esistance f and this cmbinatin is cnnected t the teminals f a V battey. The inductive time cnstant f the cicuit is (in secnds) (EAMCET 7 M) ) 5 ). 6

7 Electmagnetic Inductin Sl. Inductive time cnstant t = t = = = 5sec. 8 Hence ( is the cect chice. 3. The nth ple f a ba magnet is mved twads a cil alng the axis passing thugh the cente f the cil when viewed in the diectin f the mtin f the magnet is (EAMCET 8 M) Clckwise ) Anti - Clckwise N cuent in the cil ) Eithe clckwise anti-clckwise Ans: Sl. The diectin f the inducted cuent in the cil when viewed in the diectin f the mtin f the magnet is anti clck wise.[accding t Flemings ight hand ule] 7

Magnetism. Chapter 21

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