EASY
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The electric current in a circular coil of two turns produced a magnetic induction of 0.2 T at its centre. The coil is unwound and is rewound into a circular coil of four turns. The magnetic induction at the centre of the coil now is, in tesla (if same current flows in the coil

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Important Questions on Magnetic Effect of Current

HARD
A very long wire ABDMNDC is shown in figure carrying current I. AB and BC parts are straight, long and at right angle. At D wire forms a circular turn DMND of radius R. AB, BC parts are tangential to circular turn at N and D. Magnetic filed at the center of circle is:
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MEDIUM
The magnitude of the magnetic field at the centre of an equilateral triangular loop of side 1 m which is carrying a current of 10 A is:
[Take  μ0=4π×10-7 A-2 ]
EASY
A circular coil of wire consisting of 100 turns each of radius 9 cm carries a current of 0.4 A. The magnitude of the magnetic field at the centre of coil is μ0=12.56×107 SI Units
MEDIUM

For a plane electromagnetic wave, the magnetic field at a point x and time t is :

Bx,t=1.2×107sin0.5×103x+1.5×1011tk^ T.

The instantaneous electric field E corresponding to B is :

MEDIUM
In a certain region static electric and magnetic fields exist. The magnetic field is given by B=B0i^+2j^-4k^. If a test charge moving with a velocity v=v03i^-j^+2k^ experiences no force in that region, then the electric field in the region, in SI units, is:
MEDIUM
A particle of charge q and mass m is moving with a velocity -vi^(v0) towards a large screen placed in the Y-Z plane at distance d. If there is magnetic field B=B0k^, the minimum value of v for which the particle will not hit the screen is :
MEDIUM

Two magnetic dipoles X and Y are placed at a separation d , with their axes perpendicular to each other. The dipole moment of Y is twice that of X . A particle of charge q is passing through their mid-point P , at angle θ=45o with the horizontal line, as shown in figure. What would be the magnitude of force on the particle at that instant? ( d is much larger than the dimension of the dipole)
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EASY
A charge qo moving with velocity v in a magnetic field of induction B, experiences force F. The angle between v and B is θ. The speed of qo after one second will be
EASY
A proton, a deuteron and an α-particle with same kinetic energy enter into a uniform magnetic field at right angle to magnetic field. The ratio of the radii of their respective circular paths is :
HARD
A uniform magnetic field B exists in the region between x=0 and x=3R2 (region 2 in the figure) pointing normally into the plane of the paper. A particle with charge +Q and momentum  p directed along x -axis enters region 2 from region 1 at point P1y=-R. Which of the following option(s) is/are correct?

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EASY
The work done by a uniform magnetic field on a moving charge is,
MEDIUM

A square loop, carrying a steady current I, is placed in a horizontal plane near a long straight conductor carrying a steady current I1 at a distance d from the conductor as shown in the figure. The loop will experience
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EASY
A charged particle moves through a magnetic field perpendicular to its direction. Then
EASY
A charged particle carrying charge 1 μC is moving with velocity (2i^+3j^+4k^) m s-1. If an external magnetic field of (5i^+3j^-6k^)×10-3T exists in the region where the particle is moving then the force on the particle is F×10-9 N . the vector F is :
EASY

Consider a negatively charged particle moving with a velocity v in a magnetic field B applied perpendicular to the plane of the paper (into the paper). The particle follows the path A or B or C or D (shown in the figure)

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MEDIUM
An electron moving in a uniform magnetic field (4i^+6j^+nk^) T experiences a force (2i^+3j^+4k^) N. Then the value of n'' is
HARD

An electron enters a magnetic field of 3 i^+4 j^ T with a velocity of 6 j^+4 k^ m s-1. The acceleration produced is

(em of electron =1.76×1011 C kg-1)

HARD
A 10 cm long perfectly conducting wire PQ is moving, with a velocity 1 cm/s on a pair of horizontal rails of zero resistance. One side of the rails is connected to an inductor L=1 mH and a resistance R=1Ω as shown in figure. The horizontal rails, L and R lie in the same plane with a uniform magnetic field B=1 T perpendicular to the plane. If the key S is closed at certain instant, the current in the circuit after 1 milli second is x×10-3A, where the value of x is_______.
[Assume the velocity of wire PQ remains constant 1cm/s after key S is closed. Given: e-1=0.37, where e is base of the natural logarithm]

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HARD
If one were to apply the Bohr model to a particle of mass 'm' and charge 'q' moving in a plane under the influence of a magnetic field 'B', the energy of the charged particle in the nth level will be: