Magnetic effect of current practice · Medium

Assertion: Various regular polygons formed by a constant length current carrying wire, then magnetic induction at their centres are increases when their number of sides increases.
Reason: A magnetic dipole placed in non uniform magnetic field, then torque acting on it is always zero.

Magnetic moment for a solenoid and corresponding bar magnet is

A galvanometer has a resistance of $96\,\Omega$ and it is desired to pass $4 \%$ of the total current through it. Calculate the value of shunt resistance.

A charge particle of charge q is moving in a circle of radius R with uniform speed v. Magnetic moment M is given by

A straight horizontal wire of mass $10 \mathrm{mg}$ and length $1.0 \mathrm{~m}$ carries a current of $2.0 \mathrm{~A}$. What minimum magnetic field $B$ should be applied in the region so that the magnetic force on the wire may balance its weight?

A charged particle experiences magnetic force
in the presence of magnetic field. Which of the
following statement is correct ?

A current-carrying wire is known to produce
magnetic lines of force around the conducting
straight wire. The direction of the lines of force
may be described by:

A charge q moves with velocity ${ }^{\prime} \vec{V}{ }^{\prime}$ through electric field $(\overrightarrow{\mathbf{E}})$ as well as magnetic field $(\overrightarrow{\mathbf{B}})$. Then the force acting on it is

Tangent galvanometer measures

The magnetic field at the center of current I carrying loop of radius $r$, is

A straight current carrying conductor is kept
along the axis of circular loop carrying current.
The force exerted by the straight conductor on
the loop is :

Into a transverse uniform magnetic field of induction 6.5 G an electron is projected with a speed $4.8\mathrm{ } \times \mathrm{ }{10^6}m/s$, at angle $90^\circ$ to the boundary. The time elapsed by the electron in the field in nano second is

If number of turns in moving coil galvanometer
becomes half, then the deflection for the same
current will become

A galvanometer acting as a voltmeter should have

A voltmeter has a resistance of $G\,\,ohm$ and range $V$ volt. The value of resistance used in series to convert it into a voltmeter of range $nV$ volt is

A charge ${q}$ moves in a region where electric field and magnetic field both exist, then force on it is

The magnitude of the magnetic field produced by a current carrying loop at a large distance $x$ varies as

Statement A: When a proton and a neutron enter into a transverse magnetic field with equal speeds, then they trace circular paths of equal radii.
Statement B: In a transverse magnetic field the period of revolution of a charged particle in a circular path is directly proportional to the mass of the particle.

A charged particle moves through a magnetic
field in a direction perpendicular to it. Then it

A portion is rotating along a circular path with kinetic energy $K$ in a uniform magnetic field $B$. If the magnetic field is made four times, the kinetic energy of rotation of proton is

The force on a charged particle moving with a velocity $\overrightarrow{\mathbf{v}}$ in a magnetic field $\vec{B}$ is :

A charge $Q$ is moving $dl$ distance in the magnetic field $B$.find the value of work done by $B$.

A galvanometer, having a resistance of $\mathrm{50}\,\,\mathrm{\Omega }$, gives a full scale deflection for a current of $0.05\,\,A$. The length in meter of a resistance wire of area of cross-section $2.97\,\, \times \,\,{10^{ - 2}}\,\,\mathrm{c}{\mathrm{m}^2}$ that can be used to convert the galvanometer into a ammeter which can read a maximum of $\mathrm{5}\,\,\mathrm{A}$ current is (Specific resistance of the wire $= 5\,\, \times \,\,{10^{ - 7}}\,\,\mathrm{\Omega }\,\mathrm{m}$

In case of a charged particle moving in a non-uniform magnetic field (independent of time)

A charged particle is accelerated through potential $V_0$ is subjected to a crossed electric field $(E)$ and magnetic field $(B)$. The field are adjusted such that the charged particle is not deflected. The specific charge of particle is given by

An electron moving with constant velocity passes through a region of space without change in its velocity. If $E$ and $B$ represent electric and magnetic field respectively, the region of space may have

A maximum current of 0.5 mA can be passed through a galvanometer of resistance $20\,\,\Omega$. Calculate the resistance to be connected in series to convert it into a volt meter of resistance range.

A magnet is suspended lengthwise from a spring and while it oscillates, the magnet moves in and out of the coil C connected to a galvanometer G. Then as the magnet oscillates.

A current of $1 \mathrm{~A}$ is flowing through a straight conductor of length $16 \mathrm{~cm}$. The magnetic induction (in tesla) at a point $10 \mathrm{~cm}$ from the either end of the wire is:

For the magnetic field to be maximum due to a small element of current carrying conductor at a point, the angle between the element and the line joining the element to the given point must be