EASY
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What is the formula for magnetic field for a long solenoid?

Important Questions on Magnetic Effects of Current and Magnetism

EASY

A long solenoid is formed by winding 70 turns cm-1 . If 2.0 A current flows, then the magnetic field produced inside the solenoid is ______________.

(µ0= 4π× 107 T m A1)

EASY

Choose the correct statement in the following:

(a) The magnetic field inside the solenoid is greater than that of outside
(b) The magnetic field inside an ideal solenoid is not at all uniform
(c) The magnetic field at the centre, inside an ideal solenoid is almost twice that at the ends
(d) The magnetic field at the centre, inside an ideal solenoid is almost half of that at the ends

EASY
The space inside a straight current carrying solenoid is filled with a magnetic material having magnetic susceptibility equal to 1.2×10-5. What is fractional increase in the magnetic field inside solenoid with respect to air as medium inside the solenoid?
EASY

As shown in the figure, a long straight conductor with semicircular arc of radius π10 m is carrying current I = 3A. The magnitude of the magnetic field. at the center O of the arc is: (The permeability of the vacuum = 4π×10-7NA-2 )

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EASY

A solenoid of 1000 turns per metre has a core with relative permeability 500. Insulated windings of the solenoid carry an electric current of 5 A. The magnetic flux density produced by the solenoid is:

(Permeability of free space=4π×10-7 H m-1)

EASY

A rod with circular cross-section area 2 cm2 and length 40 cm is wound uniformly with 400 turns of an insulated wire. If a current of 0.4 A flows in the wire windings, the total magnetic flux produced inside windings is 4π×10-6 Wb. The relative permeability of the rod is

(Given : Permeability of vacuum μ0=4π×10-7 N A-2)

MEDIUM
Torque required to hold a small circular coil of 10 turns, 2×10-4 m2 area and carrying 0.5 A current is the middle of a long solenoid of 103 turns per meter carrying 3 A current, with its axis perpendicular to the axis of the solenoid is
MEDIUM
One of the two identical conducting wires of length L is bent in the form of a circular loop and the other one into a circular coil of N identical turns. If the same current is passed in both, the ratio of the magnetic field at the centre of the loop BL to that at the centre of the coil BC, i.e. BLBC will be
EASY

Four identical long solenoids A, B, C and D are connected to each other as shown in the figure. If the magnetic field at the center of A is 3 T the field at the center of C would be : (Assume that the magnetic field is confined with in the volume of respective solenoid).

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EASY
A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of magnetic field will be equal to
EASY
The current required to be passed through a solenoid of 15 cm length and 60 turns in order to demagnetise a bar magnet of magnetic intensity 2.4×103 A m1 is ________ A.
EASY
A galvanometer coil has 500 turns and each turn has an average area of 3×10-4m2. If a torque of 1.5 Nm is required to keep this coil parallel to a magnetic field when a current of 0.5A is flowing through it, the strength of the field (in T) is _________ .
EASY
The magnetic intensity at the centre of a long current carrying solenoid is found to be 1.6 ×103 A m-1. If the number of turns is 8 per cm, then the current flowing through the solenoid is ______A.
MEDIUM
A solenoid of 1200 turns is wound uniformly in a single layer on a glass tube 2 m long and 0.2 m in diameter. The magnetic intensity at the center of the solenoid when a current of 2 A flows through it is:
MEDIUM
A long straight wire of radius a carries a steady current I . the current is uniformly distributed over its cross-section. The ratio of the magnetic fields B and B' , at radial distances a2 and 2a respectively, from the axis of the wire is:
EASY
An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the center has magnitude:
MEDIUM
Two infinitely long straight wires lie in the xy - plane along the lines x=±R. The wire located at x = +R carries a constant current I1 and the wire located at x =-R carries a constant current I2. A circular loop of radius R is suspended with its centre at 0, 03R and in a plane parallel to the xy - plane. This loop carries a constant current I in the clockwise direction as seen from above the loop. The current in the wire is taken to be positive if it is in the +j^ direction. Which of the following statements regarding the magnetic field B is (are) true?
MEDIUM
The value of aluminium susceptibility is 2.2×10-5. The percentage increase in the magnetic field if space within a current carrying toroid is filled with aluminium is n104. Then the value of n is
EASY
A toroid has an iron core with an internal magnetic field of 10πmT, when the current in the winding of 1500 turns per meter is 10 A. Deternine the field due to magnetization μ0=4π×10-7Hm-1
EASY
A toroid has 500 turns per unit length. If it carries a current of 2 A, the magnetic energy density inside the toroid is