NEET Physics MCQs

The expression for magnetic induction inside a solenoid of length L, carrying a current i and having N number of turns is

A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2m, 100 turns, and carrying a current of 5.2 A. The coercivity of the bar magnet is:

A bar magnet has coercivity $4 imes {10^3}\;A{m^{ - 1}}$. It is desired to demagnetise it by inserting it inside a solenoid $12\;cm$ long and having 60 turns. The current that should be sent through the solenoid is

An iron rod of volume ${10^{ - 4}}\;{m^3}$ and relative permeability 1000 is placed inside a long solenoid wound with $5\;turns/cm$. If a current of 0.5 $A$ is passed through the solenoid, then the magnetic moment of the rod is

A solenoid has ${\rm{2000}}$ turns wound over a length of ${\rm{0}}.{\rm{30}}\,\,{\rm{m}}$. The area of its cross-section is $1.2\,\, imes {10^{ - 3}}\,{{\rm{m}}^2}$. Around its central section a coil of ${\rm{300}}$ turns is wound. If an initial current of ${\rm{2 A}}$ in the solenoid is reversed in ${\rm{0}}{\rm{.25}}\,\,{\rm{s}}$, the emf induced in the coil is

A solenoid is $1.5\,\,m$ long and its inner diameter is $4.0\,\,cm$. It has three layers of windings of $1000$ turns each and carries a current of $2.0\,\,amperes$. The magnetic flux for a cross-section of the solenoid is nearly

A short solenoid of length ${\rm{4}}\,\,{\rm{cm}}$, radius ${\rm{2}}\,\,{\rm{cm}}$ and ${\rm{100}}$ turns is placed inside and on the axis of a long solenoid of length ${\rm{80}}\,\,{\rm{cm}}$ and ${\rm{1500}}$ turns. A current of ${\rm{3}}\,\,{\rm{A}}$ flows through the short solenoid. The mutual inductance of two solenoids is

A long solenoid of ${\rm{50}}\,\,{\rm{cm}}$ length having ${\rm{100}}$ turns carries a current of ${\rm{2}}{\rm{.5}}\,\,{\rm{A}}$. The magnetic field at the centre of the solenoid is : ${\rm{(}}{{\rm{\mu }}_0}\,{\rm{ = }}\,4{\rm{\pi }}\,\,{\rm{ imes }}\,\,{\rm{1}}{{\rm{0}}^{ - 7}}\,\,{\rm{T}}\,{\rm{m}}\,{{\rm{A}}^{ - 1}})$

A long solenoid of diameter $0.1\;{\rm{ m\; has\; 2}} imes {\rm{1}}{{\rm{0}}^4}$ turns per meter. At the centre of the solenoid, a coil of 100 turns and radius $0.01\;{\rm{ m}}$ is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to ${\rm{0A\; from\; 4A \;in\; 0}}{\rm{.05\; s}}$. if the resistance of the coil is $10{\pi ^2}\Omega \,,$ the total charge flowing through the coil during this time is

A long solenoid of diameter $0.1\;{\rm{ m\; has\; 2}} imes {\rm{1}}{{\rm{0}}^4}$ turns per meter. At the centre of the solenoid, a coil of 100 turns and radius $0.01\;{\rm{ m}}$ is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to ${\rm{0A\; from\; 4A \;in\; 0}}{\rm{.05\; s}}$. if the resistance of the coil is $10{\pi ^2}\Omega \,,$ the total charge flowing through the coil during this time is