iCON Education - Magnetism and Matter TS-EAMCET Test

At a certain place in the magnetic meridian the Earth's magnetic field is twice its vertical component. The ratio of horizontal component of Earth's magnetic field and the total magnetic field of the Earth at the place is

A short bar magnet of magnetic moment $2.5 \mathrm{Am}^2$ is kept in a uniform magnetic field of $4 \times 10^{-5} \mathrm{~T}$. The work done in moving the magnet from its most stable position to most unstable position is

$40 \times 10^{-5} \mathrm{~J}$

$25 \times 10^{-5} \mathrm{~J}$

$10 \times 10^{-5} \mathrm{~J}$

$20 \times 10^{-5} \mathrm{~J}$

The magnetic field at a point $P$ on the axis of a short bar magnet of magnetic moment $M$ is $B$. If another short bar magnet of magnetic moment 2 M is placed on the first magnet such that their axes are perpendicular and their centres coincide. The resultant magnetic field at the point $P$ due to both the magnets is

If $B_V$ and $B_H$ are respectively the vertical and horizontal components of the Earth's magnetic field at a place where the angle of $\operatorname{dip}$ is $60^{\circ}$, then the total magnetic field at that place is

$\frac{2}{\sqrt{3}} B_v$

$\frac{\sqrt{3}}{2} B_H$

If the magnetic susceptibility of a substance is 0.6 , then the ratio of permeability of the substance and permeability of free space is

The magnetising field which produces a magnetic flux of $22 \times 10^{-6} \mathrm{~Wb}$ in a metal bar of area of cross-section $2 \times 10^{-5} \mathrm{~m}^{2}$ is (susceptibility of the metal $=699$ )

$2500 \mathrm{Am}^{-1}$

$1250 \mathrm{Am}^{-1}$

$3750 \mathrm{Am}^{-1}$

$5000 \mathrm{Am}^{-1}$

A short bar magnet placed in a uniform magnetic field making an angle with the field experiences a torque.If the angle made by the magnet with field is changed from $30^{\circ}$ to $45^{\circ}$, the torque on the magnet

increases by $50 \%$

decreases by $50 \%$

decreases by $41.4 \%$

increases by $41.4 \%$

If a bar magnet of moment $10^{-4} \mathrm{Am}^2$ is kept in a uniform magnetic field of $12 \times 10^{-3} \mathrm{~T}$ such that it makes angle of $30^{\circ}$ with the direction of magnetic field, then the torque acting on the magnet is

$6 \times 10^{-7} \mathrm{~N}-\mathrm{m}$

$6 \times 10^{-5} \mathrm{~N}-\mathrm{m}$

$12 \times 10^{-7} \mathrm{~N}-\mathrm{m}$

$12 \times 10^{-5} \mathrm{~N}-\mathrm{m}$

The most exotic diamagnetic materials are

A bar magnet of magnetic moment $2 \mathrm{~A}-\mathrm{m}^2$ lies aligned with the direction of a uniform magnetic field of 0.3 T . The amount of work required by an external torque to turn the magnet so as to align its magnetic moment normal to the field direction is

If $\chi$ is the susceptibility and $\mu_r$ is the relative permeability of a ferromagnetic substance, then

The period of oscillation of a bar magnet at a place is 2 s . At the same place, the period of oscillation of another identical bar magnet whose magnetic moment is 4 times so that of first magnet is

materials suitable for permanent magnets, must have which of the following properties?

High retentivity, low coercivity and high permeability.

Low retentivity, low coercivity and low permeability.

Low retentivity, high coercivity and low permeability.

High retentivity, high coercivity and high permeability.

The expression for the magnetic energy stored in a solenoid of length $L$, in terms of magnetic field $B$ and area $A$ is

$\frac{1}{2 \mu_0} B^2 A L$

$\frac{1}{2 \varepsilon_0} B^2 A L$

$\frac{1}{2 \mu_0} B A^2 L$

$\frac{1}{2 \varepsilon_0} B A^2 L$

The magnetic susceptibility of ferromagnetic materials is

A bar magnet has coercivity $4 \times 10^3 \mathrm{Am}^{-1}$. It is placed inside a solenoid of 12 cm length and 60 turns. The current that should be passed through the solenoid to demagnetise, the bar magnet is

In the magnetic meridian of a certain place, the horizontal component of the earth's magnetic field is 86.6 G (Gauss) and the magnetic field of earth is 100 G (Gauss). The the dip angle is

An iron bar having a cross-sectional area of $2 \times 10^{-5} \mathrm{~m}^2$ and magnetising field of $2400 \mathrm{~A} / \mathrm{m}$ produce a magnetic flux $2.4 \pi \times 10^{-5} \mathrm{~Wb}$. What will be the value of permeability $\mu$ and susceptibility $\chi$ of the bar (given, $\mu_0=4 \pi \times 10^{-7}$ )

$\mu=5 \times 10^{-4}, \chi=1249 \pi$

$\mu=5 \pi \times 10^{-4}, \chi=1249 \pi$

$\mu=5 \pi \times 10^{-4}, \chi=1249$

$\mu=5 \times 10^{-4}, \chi=1249$

The magnitude of axial field due to a bar magnet at a distance of 1 m , is found to be $5 \times 10^{-8} \mathrm{~T}$. The magnetic moment of the bar magnet is $\left(\mu_0=4 \pi \times 10^{-7}\right)$

$0.20 \mathrm{~A}-\mathrm{m}^2$

$0.25 \mathrm{~A}-\mathrm{m}^2$

$0.50 \mathrm{~A}-\mathrm{m}^2$

$0.40 \mathrm{~A}-\mathrm{m}^2$

A thin magnetic needle is placed in a magnetic field of 200 G with its axis at $30^{\circ}$ to the direction of the field. Find the magnetic moment of the needle, if it experiences a torque of 0.012 Nm in this field.

$1.2 \mathrm{~A}-\mathrm{m}^2$

$12.0 \mathrm{~A}-\mathrm{m}^2$

$0.6 \mathrm{~A}-\mathrm{m}^2$

$6.0 \mathrm{~A}-\mathrm{m}^2$

Assertion (A) The magnetic field lines are continuous and form closed loops. Reason (R) Magnetic monopole does not exist. The correct option among the following is

(A) is true, (R) is true and (R) is the correct explanation for (A).

(A) is true, (R) is true but (R) is not the correct explanation for $(A)$.

(A) is true but (R) is false.

(A) is false but (R) is true.

A planet has magnetic dipole moment of $27 \times 10^{22} \mathrm{~A}-\mathrm{m}^2$. If the radius of the planet is 300 km , what would be the magnetic field at its equator? $\left(\right.$ use,$\left.\frac{\mu}{4 \pi}=10^{-7}\right)$

A solenoid has a core of a material with relative permeability $\frac{800}{\pi}$. The windings of the solenoid are insulated from the core and carry current of 2 A . If the number of turns is 1000 per metre, find the magnetic field $B$.

Which of the following is desirable for making permanent magnets?

Low coercive field and low retentivity

Low coercive field and high retentivity

High coercive field and high retentivity

High coercive field and low retentivity

Two short magnets of equal dipole moments $M$ are fastened perpendicularly at their centres which lies at origin. Let two magnets lie along $X$-axis and $Y$-axis, respectively.

The magnitude of the magnetic field at a distance $R$ from the centre on the $Y$-axis is $\frac{\mu_0}{4 \pi} \frac{M_0}{R^3}$. Assuming, $R \gg l$ (magnet length), the magnitude of $M$ is

$\frac{M_0}{2 \sqrt{2}}$

$\frac{M_0}{\sqrt{5}}$

$\frac{M_0}{\sqrt{2}}$

If relative permeability of iron is 5500 , then its susceptibility is

$5500 \times 10^{-7}$