A straight wire $AB$ of mass $40\,g$ and length $50\,cm$ is suspended by a pair of flexible leads in uniform magnetic field of magnitude $0.40\,T$ as shown in the figure. The magnitude of the current required in the wire to remove the tension in the supporting leads is ...........$A$. (Take $g=10\,ms ^{-2}$ ).
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Two very long, straight, parallel wires carry steady currents $I$ and $-I$ respectively. The distance etween the wires is $d$. At a certain instant of time, a point charge $q$ is at a point equidistant from the two wires, in the plane of the wires. Its instantaneous velocity $v$ is perpendicular to the plane of wires. The magnitude of the force due to the magnetic field acting on the charge at this instant is
A straight wire of length $0.5\, metre$ and carrying a current of $1.2\, ampere$ placed in a uniform magnetic field of induction $2\, Tesla$. The magnetic field is perpendicular to the length of the wire. The force on the wire is.......$N$
A milliammeter of range $10\, mA$ has a coil of resistance $1 \,\Omega$. To use it as voltmeter of range $10\, volt$, the resistance that must be connected in series with it, will be ............. $\Omega $
A spherical shell of radius $'R'$ carries uniformly distributed charge $'Q'$ is rotated about it's diameter with angular speed $\omega $ find it's magnetic moment
An ion beam of specific charge $5 \times 10^7$ $coulomb/kg$ enter a uniform magnetic field of $4 \times 10^{-2}\, tesla$ with a velocity $2 \times 10^5\, m/s$ perpendicularly. The radius of the circular path of ions in meter will be
A circular coil is in $y-z$ plane with centre at the origin. The coil is carrying a constant current. Assuming direction of magnetic field at $x = -25\, cm$ to be positive direction of magnetic field, which of the following graphs shows variation of magnetic field along $x-$ axis
A circular conducting loop of radius $R$ carries a current $I.$ Another straight infinite conductor carrying current $I$ passes through the diameter of this loop as shown in the figure. The magnitude of force exerted by the straight conductor on the loop is
There are three voltmeters of the same range but of resistances $10000\,\Omega $, $8000\,\Omega $ and $4000\,\Omega $ respectively. The best voltmeter among these is the one whose resistance is ................ $\Omega $
The figure below shows the north and south poles of a permanent magnet in which $n$ turn coil of area of cross-section $A$ is resting, such that for a current $ i$ passed through the coil, the plane of the coil makes an angle $\theta $ with respect to the direction of magnetic field $B.$ If the plane of the magnetic field and the coil are horizontal and vertical respectively, the torque on the coil will be