Magnetic Field Questions and Answers

3 A particle of mass m and charge q moves with a constant velocity v along the positive x direction It enters a region containing a uniform magnetic field B directed along the negative z direction extending from x a to x b The minimum value of v required so that the particle can just enter the region x b is a qbB m c qaB m b q b a B m d q b a B 2m 37

33 There are two stationary fields of force F ayi and F axi byj where i and j are the unit vectors of the x and y axes and a and b ar constants Find out whether these fields are potential

A long wire carries a current of 90A from east to we direction Magnetic field due to current at a poi which is 1 5 m vertically below the wire 1 12 x 10 6 T towards north 2 6x10 6T towards south 3 12 x 10 6 T towards south 4 6 x 10 6 T towards north

A long straight wire of radius a carries a steady current I The current is uniformly distributed across its cross section The ratio of the magnetic field at a 4 is 1 1 1 2 7 16 1 3 inside and outside from the surface of wire 4 NCERT Pg 149 a 15 16 Uo 0

Twelve indentical capacitors each of capacitance C are connected as shown in figure 6C A The effective capacitance between P and T is 5 B The effective capacitance between P and U is 4C 3 12C C The effective capacitance between P and V is D All of the above statements are incorrect U Ans A B C

55 The magnetic field dB due to a small current element dl at a distance 7 and element carrying current i is a dB 02 di xr 4T i 4t b dB Ho i 4 c dB Ho r TT d dB 02 4t dl xr di x r di x 7 1996

In the figure shown a coil of single turn is wound on a sphere of radius r and mass m The plane of the coil is parallel to the inclined plane and lies in the equatorial plane of the sphere If the sphere is in rotational equilibrium the value of B is current in the coil is i A mg sine B Ti C mg Tir mgr sine Ti D none of these D 100

30 Choose the correct statement 1 It is possible for a current loop to stay without rotating in a uniform magnetic field 2 If a uniform magnetic field exists in a cubical region and zero outside then it is not possible to project a charged particle from outside into the field so that it describes a complete circle in the field 3 A moving charged particle can be accelerate by a magnetic field 4 All of these

Q7 A wire loop with a 10 0 cm and b 15 0 cm and a long straight wire is arranged as shown in figure The current in the wire is changing according with a relation i 5 0t 10 0t where i is in amperes and t is in seconds K b b a Find the emf in the square loop at t 4 0 s b What is the direction of the induced current in the loop

A hollow non conducting sphere of radius R has a positive charge q uniformly distributed on its surface The sphere starts rotating with a constant angular velocity o about an axis passing through center of sphere as shown in the figure Then the net magnetic field at center of the sphere is A B C How 2 R How 6 R D Ho9 3 R Hoq 12TR O 9 R

Find The area enclosed by a circular coil of 2000 turns is 10 cm Its plane is kept perpendicular to a magnetic field of 0 3 Wb m2 and is rotated through 180 Calculate the magnitude of change in magnetic flux

A flat coil with radius 8 mm has fifty loops of wire on it It is placed in a magnetic field of 0 3 T so that the maximum flux goes through it Later it is rotated in 0 02 s to a position such that no flux goes through it Find the average emf induced between the terminals of the coil Two concentric pirou

target Find the force imparted by the beam on the target if the beam current is equal to I 1 An infinite uniform current carrying wire is kept along z axis carrrying current I in the direction of the positive z axis OABCDEFG represents a circle where all the points are equally spaced whose centre at point 4m 0 m and radius 4 m as shown in the figure If B d DEF unit then find the value of k YA E 00 4m 0 m D A Holo in S I A shus grinde OLD BIS A Stries Horlw tomoubnoo

and q masses m and m and having rad R and R respectively are rotating wit angular velocity o then the gyro magnetic rati of the system will be x 40 R q R q R 1 2 m R m R 9 92 3 2 m R m R2 x XX R XX i xxx q R q R 2 2 m m 4 None

A particle of specific charge q m is projected from the origin of coordinates with initial velocity ui vj Uniform electric and magnetic fields exist in the region along the y direction of magnitude E and B The particle will definitely return to the origin once if B u v 2 B TE is an integer D uB TE is an integer odi nwone A VB 2TE is an integer C VB TE in an integer peopubnoo gnol owT

A long cylindrical volume contains a uniformly distributed charge of density p Find the flux due to the electric field through the curved surface of the small cylinder whose axis is OP and whose radius is a Here O lies on the axis AB of the main cylinder containing the charge density p and its axis OP is perpendicular to AB and lies completely within the main cylinder A 60 X B