List of top Physics Questions on Magnetic Field asked in NEET (UG)

In a uniform magnetic field of 0.049T0.049 T, a magnetic needle performs 2020 complete oscillations in 55 seconds as shown. The moment of inertia of the needle is 9.8×10kgm29.8 \times 10 kg m^2. If the magnitude of magnetic moment of the needle is x×10−5Am2x \times 10^{-5} Am^2; then the value of 'xx' is
 

Magnetic field
A tightly wound 100100 turns coil of radius 10cm10 cm carries a current of 7A 7 A. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as 4π×10−74\pi×10^{-7} SI units):
An iron bar of length L has magnetic moment M. It is bent at the middle of its length such that the two arms make an angle 60° with each other. The magnetic moment of this new magnet is :
A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to :
A. hold the sheet there if it is magnetic.
B. hold the sheet there if it is non-magnetic.
C. move the sheet away from the pole with uniform velocity if it is conducting.
D. move the sheet away from the pole with uniform velocity if it is both, non-conducting and non-polar.
Choose the correct statement(s) from the options given below :

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : The potential (V) at any axial point, at 2 m distance(r) from the centre of the dipole of dipole moment vector

 P⃗\vec{P} of magnitude, 4 × 10-6 C m, is ± 9 × 103 V.
      (Take 14πϵ0=9×109\frac{1}{4\pi\epsilon_0}=9\times10^9 SI units)
 

Reason R : V=±2P4πϵ0r2V=±\frac{2P}{4\pi \epsilon_0r^2}, where r is the distance of any axial point, situated at 2 m from the centre of the dipole.
In the light of the above statements, choose the correct answer from the options given below :

A wire of length LL metre carrying a current of II ampere is bent in the form of a circle. Its magnetic moment is,
A bar magnet placed in a uniform magnetic field making an angle θ\theta with the field experiences a torque. If the angle made by the magnet with the field is doubled, the torque experienced by the magnet increases by 41.4%41.4\%. The initial angle made by the magnet with the magnetic field is
Ionized hydrogen atoms and a-particles with same momenta enters perpendicular to a constant magnetic field, B. The ratio of their radii of their paths rH:rα r_H: r_\alpha will be:
A 800 turn coil of effective area 0.05 m20.05\ m^2 is kept perpendicular to a magnetic field 5×10−5T. 5 \times 10^{-5} T. When the plane of the coil is rotated by 90°90\degree around any of its coplanar axis in 0.1s0.1 s, the emf induced in the coil will be:
At a point A on the earth's surface the angle of dip, δ=+25°\delta=+25°. At a point B on the earth's surface the angle of dip, δ=−25°\delta=-25°. We can interpret that: 
An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude
Two identical long conducting wires AOB and COD are placed at right angle to each other, with one above other such that 'O' is their common point for the two. The wires carry I1 and I2 currents, respectively. Point 'P' is lying at distance 'd' from 'O' along a direction perpendicular to the plane containing the wires. The magnetic field at the point 'P' will be:
A current loop in a magnetic field
A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced
Tesla is the unit of
Two equal electric currents are flowing perpendicular to each other as shown in the figure. AB and CD are perpendicular to each other and symmetrically placed with respect to the currents. Where do we expect the resultant magnetic field to be zero?
A 100 millihenry coil carries a current of 1 A. Energy stored in its magnetic field is
The magnetic induction at a point P which is at the distance of 4 cm from a long current carrying wire is 10−3 10^{-3} T. The field of induction at a distance 12 cm from the current will be