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Biot Savart’s Law, , A. The unit of current clement is :, , (A) Am7! (B) Am, , (C) Am? (D) Am-2, , 2. The magnetic field due to a current, element is independent of :, , (A) current through it, , (B) distance from it, , (C) its length, , (D) none of the above., , 3. Magnetic ficld B on the axis of a circular, coil and far away distance x from the Centre gf, the coil are related as :, , (A) B «x73, (C)Bax!, , (B) B «x?, (D) none of the above,, , A. If we double the radius of a current, carrying coil keeping the current unchanged,, what happens to the magnetic field at its, centre ?
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(A) Becomes four times, , (B) Doubled ., , (C) Remains unchanged, , {D) Halved,, , §/If we double the radius of a coil keeping the, current through it unchanged, what happens to, the magnetic ficld on its axis at very very far away, points ?, , (A) Becomes four times, , (B) Doubled, , (C) Remains unchanged, , (D) Halved,, , @6,A current carrying coil is placed with its, plane in the magnetic meridian of the earth. When, scen from the cast side a clockwise current is sel, up in the coil. The magnetic field at its centre will, be directed towards :, , (A) North (B) South, , (C) West (D) East, , A current carrying power line carries, current from west to cast. What will be the, direction of magnetic field 1m above it ?, , (A) North to south (B) South to north, , (C) East to west (D) West to east., , $.’Two concentric coils carry the same current, in opposite directions. The diameter of the outer, coil is twice as compared to the inner coil. If at its, centre , the smaller coil produces a magnetic field, of 27, then, the magnetic field at the common, centres is:, , (A) 4T (B) 3T, , (c)2T (D) 17. :, , .9An infinite straight current carrying, conductor is bent into acircle as shown in the, fig, Q-9.1. If the radius of the circle is R, the, magnetic ficld at the centre of the coil is :, , sae M, , Fig. 0.9.1, , ' (A) Infinite, (B) Zero, Mo 2, , Ga R, , (C), , , , My U 991, , (Day R A+., , 10. The strength of the m ic fie, an infinite mere carrying miei oe, , (A) same every where, , (B) inversely proportional to the distance, , (C) inversely proportional to the square of the, distance, , (D) directly proportional to the distance,, , and Q are two points at the same distance, , and in the’ same horizontal plane from a current, carrying vertical conductor. The point P is located, towards west and the point O is towards east. The, current is vertically downwards. If B, and B, be, the net magnetic fields at P and Q ; then, , (A) B, =B,, , (B)B,> B,, , (C)B, < B,, , (D) Any one of the above relation may be true, depending on the strength of current., , . A metallic rod carrics direct current., Which of the following statements about the, existence of magnetic ficld is true ?, , (A) It exists outside only, (B) It exists inside only, -(C) It exists both inside and outside., ye It exists neither inside nor outside,, . 8. A metallic pipe carries direct current., Which of the following statements about the, existence of magnetic field is true ?, (A) It exists outside only, (B) It exists inside only, (C) It exists both inside as well as outside, (D) It exists neither inside nor outside,, Ja. An infinite long straight wire is bent into a, semicircle of radius R, as shown in the figure,, , Acurrent / is sent through the conductor, The, magnetic field at the centre of the semicircle is :, , 1, I > :, Fig Q-14.1, (A) infinite (B) zero, Howl Mo I, oe Oa Ret
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S.A Current carrying coil is bent sharply so, aSto convert itinto a double loop both carrying, current in the same direction, If B be the initial, magnetic field at the centre, what will be the final, concentric magnetic field ? :, , (A) 2B (B) 4B, (CG) 8B (D) Zero,, . In the question 15, what will be the final, magnetic field, if the current in the two coils is, opposite to each other ?, , (A) 2B (B) 4B, , o (D) Zero., , Wi. A circular are of wire subtends an angle, x/2at the centre. If it carries a current / and, its radius of curvature is R, then the magnetic ficld, at the centre of the arc is:, , (A) #,1/R (B) 4, 1/2R, , (Cyb, I/4R (D) 4, 1/8R,, aoe circular coil of radius R carries a, current J, The magnetic field at its centre is B. At, what distance from the centre, on the axis of the, coil the magnetic field will be B/8 ?, (A)VZR (B) VIR, (C) 2R (D) 3R., WS. Which of the tollowing graphs shows the, , variation of magnetic field B, with distance from, along current carrying conductor ?, , ae eID ELECTHOM ag, , (A) Infinity (B) Zero, “ye 2 Ky, OfT ois, PA. Magnetic field duc to a curren,, toroidal solenoid is independent of :, (A) Sts number of turns, (B) Current, (C) Radius, (D) None of the above., 72, What is the magnetic field in the em,, space enclosed by the toroidal solenoid of radiy,, R?, , iN, , L, :, , Carrying, , (A) Infinity Ho 2, , BR, , Ho at (D) Zero., (©) 4x R, , 23. What is the magnetic field in the space, outside the toroidal solenoid of radius R ?, A) Infinity Ho dat, ¢ >, &% J (D) Zero., (an *R, a The magnetic field inside a toroidal, solenoid of radius R is B. If the current through it, is doubled and its radius is also doubled, keeping the number of turns perunit length the, same magnetic ficld produced by it will be :, (A) 4B (B) 2B, (C)B/2 (D) B/4., \ 28. What is the magnetic field at the point of, intersections of diagonals of a current {carrying, square loop of cach side L, The current through, , , , , , prong ee the loop is /., oe ma (aye V27 (py He 421, 4x L 4x L, B B ©) Ma 8V2 1 (D) None of the aboweI t ax L, Lorentz Force, nfm ie 26. “A charge is fired through a magnetic fed, The force acting on itis maximum when the Fig. Q-19.1 between the direction of motion and magne, i i field is :, . 20° What is the magnetic field produced by L, i ery thin) current (A) Zero (B) 2/4, metre long straight (very-very thin) () ao ae, , carrying conductor al any point on the conductor, , itsclf ?
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ah No. force acts on the charge fired through, a magnetic field, when the angle between its, velocity and magnetic field is, , (A) (B) 30r/4, (C) 2/2 (D) 2/4, 28. Out of F,# and B in the relation, , F, =4q (@ x B), which of the following pairs can, have any angle between them ?, , (A) and B (B) Fo andi®, , (C)F, and B (D) None of the above., 20 win, , (A)NAm (B)NA~ mm!, (C)NA 'm (D)NAm!,, , 30. Which of the following is not the unit of, » magnetic induction ?, (A) tesla (B) gauss, (C) oersted (D) weber/meter*, +The dipole moment of a current loop is, independent of ;, (A) current in the loop, (B) number of turns, (C) area of the loop, (D) magnetic field in which it is situated., 32. A charged particle moves through a, magnetic field directed perpendicular to its, direction of motion. Which of the following, quantities of the particle will not change ?, (A) Momentum (B) Speed, (C) Velocity (D) None of the above., _33. A proton enters a magnetic ficld with, velocity parallel to the magnetic ficld. The nature, of the path followed by the proton will be :, (A) straight linc (B) circle, (C) helix (D) parabola., Direction for Q.34 to 43, A test charge q, enters a magnetic field B,, which is directed along the Z-axis, The velocity of, test. charge is @ and it makes angle @ with B,, Answer the questions 34 to 43, ve What will be the speed of the test charge, after one second ?, (A) v/B (B)e, (C)uB : (D) None of the above., ‘ 380 Which of the following characteristics of, the test charge donot change with time ? Assume, thatg # 0. ., , ws, , (A) Momentum (8) Kinetic energy, (C) Acceleration (1D) Direction of motion,, » 46. If @ =0, which of the following, change, with time ?, (A) Momentum ({B) Kinetic energy, (C) Acceleration (D) None of the above., 37. If is neither 0° nor 90°, the path of the, test charge is +, (A) circular (B) straight line, (C) helix (D) parabola., 38. If. 4 be the mass of the charged particle,, which cnters with velocity v normal to the, magnetic field B, it will revolve with angular, , specd given by:, , , , (A) q, BM (B) GoM, B, B B, of aa, , 39. What is the time rate of work done by the, magnetic field 6n the test charge, when it follows, a_helical-path ?, , (A) q)B (B) q,B/v, , {C)q,Bu" (D) Zero., , . The radius of the circular path or helical, path followed by the test charge where ¢ = 0, is, , (A) Mv sin@/q,B — (B) Mv cos@/q,B, (C) Mv/q,B (D) Mv tan @/q, B., 4 In which direction no change in, momentum of test charge occurs ?, (A) Along Z-axis, (B) Along Y-axis, (C) Along X-axis, (D me angle ¢ with the X-axis,, 42. Which of th i i, particle is cinema si rh, —, - (A) Momentum, (B) Kinetic energy, (C) Centripetal force, (D) Ceatripetal acceleration,, 6 AS, Which of the following characteristics is, independent of the angle between Gand B., (A) Momentum, (B) Radius of helical path
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(©) Angular speed, , (D) None of the above., , 44. A positively charged particle falls vertically, downwards. The horizontal component of the, carth’s magnetic field will deflect it towards :, , (A) West (B) East, , (C) South (D) North,, , 48. An clectron and a proton enter a, magnetic field with equal velocities.- Which one of, them experiences more force ?, , (A) Electron, , (B) Proton, , (C) Both experience same force, , (D) It cannot be predicted., , sat a “ ’
