Magnetism and Matter

A fighter plane of length 20 m, wing span (distance from tip of one wing to the tip of the other wing) of 15 m and height 5 m is flying towards east over Delhi. Its speed is 240 ms$^{-1}$. The earth's magnetic field over Delhi is $5\times10^{-5}$ T with the declination angle ~0° and dip of θ such that $\sin\theta=\dfrac23$. If the voltage developed is $V_B$ between the lower and upper side of the plane and $V_W$ between the tips of the wings then $V_B$ and $V_W$ are close to :

A 25 cm long solenoid has radius 2 cm and 500 total number of turns. It carries a current of 15 A. If it is equivalent to a magnet of the same size and magnetization $\vec M$ (magnetic moment/volume), then $|\vec M|$ is :

A short bar magnet is placed in the magnetic meridian of the earth with north pole pointing north. Neutral points are found at a distance of 30 cm from the magnet on the East - West line, drawn through the middle point of the magnet. The magnetic moment of the magnet in Am$^2$ is close to :

(Given $\dfrac{\mu_0}{4\pi}=10^{-7}$ in SI units and $B_H$ = Horizontal component of earth's magnetic field = $3.6\times10^{-5}$ Tesla.)

The coercivity of a small magnet where the ferromagnet gets demagnetized is $3\times10^3$ A m$^{-1}$. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is :

The mid points of two small magnetic dipoles of length $d$ in end-on positions, are separated by a distance $x$, ($x\gg d$). The force between them is proportional to $x^{-n}$ where $n$ is :

The magnetic field of earth at the equator is approximately $4\times10^{-5}$ T. The radius of earth is $6.4\times10^6$ m. Then the dipole moment of the earth will be nearly of the order of :

Three identical bars A, B and C are made of different magnetic materials. When kept in a uniform magnetic field, the field lines around them look as follows :

Make the correspondence of these bars with their material being diamagnetic (D), ferromagnetic (F) and paramagnetic (P) :

An example of a perfect diamagnet is a superconductor. This implies that when a superconductor is put in a magnetic field of intensity B, the magnetic field $B_s$ inside the superconductor will be such that :