NEET Physics MCQs

A boat is moving due east in a region where the earth’s magnetic field is $5.0 imes {10^{ - 5}}\,\,{\rm{N}}{{\rm{A}}^{ - 1}}{{\rm{m}}^{ - 1}}$ due north and horizontal. The boat carries a vertical aerial $1{\mkern 1mu} {\rm{2}}\,{\rm{m}}$ long. If the speed of the boat is ${\rm{1}}{\rm{.50}}\,\,{\rm{m}}{{\rm{s}}^{ - 1}}$, the magnitude of the induced emf in the wire of aerial is

An axle of truck is ${\rm{2}}{\rm{.5 m}}$ long. If the truck is moving due north at $30\,\,m{s^{( - 1)}}$ at a place where the vertical component of the earth’s magnetic field is $90\,\,\mu T$, the potential difference between the two ends of the axle is

The two rails of a railway track insulated from each other and the ground are connected to a milli-voltmeter. What is the reading of the ${\rm{mV}}$, when a train travels at a speed of ${\rm{180}}\,\,{\rm{km}}{{\rm{h}}^{ - 1}}$ along the track, given that the horizontal components of earth’s magnetic field is $0.2 imes {10^{ - 4}}\,\,{\rm{Wb}}{{\rm{m}}^{ - 2}}$ and the rails are separated by ${\rm{1 m}}$

A horizontal straight wire ${\rm{10 m}}$ long extending from east to west is falling with a speed of ${\rm{5}}{\rm{.0}}\,\,{\rm{m}}{{\rm{s}}^{{\rm{( - 1)}}}}$, at right angles to the horizontal component of the earth’s magnetic field of strength $0.30 imes {10^{ - 4}}\,\,{\rm{Wb}}{{\rm{m}}^{ - 2}}$. the instantaneous value of the induced potential gradient in the wire, from west to east, is

The magnetic induction in the region between the pole faces of an electromagnet is $0.7\,\,weber/{m^2}$. The induced e.m.f. in a straight conductor $10\,\,cm$ long, perpendicular to $B$ and moving perpendicular both to magnetic induction and its own length with a velocity $2\,\,m/\sec$ is

When a rod of length $l$ is rotated with angular velocity of $\omega$ in a perpendicular field of induction $B$, about one end, the emf across its ends is

A coil has an area of $0.05\,\,{m^2}$ and it has ${\rm{800}}$ turns. It is placed perpendicularly in a magnetic field of strength $4 imes {10^{ - 5}}\,\,Wb/{m^2}$, it is rotated through $90^\circ$ in $0.1\,\sec$. The average e.m.f. induced in the coil is

A circular wire of radius $r$ rotates about its own axis with angular speed $\omega$ in a magnetic field $B$ perpendicular to its plane, then the induced emf is

A varying current at the rate of $3\,\,A/s$ in a coil generates an e.m.f. of $8\,\,mV$ in a nearby coil. The mutual inductance of the two coils is

Armature current in dc motor will be maximum when