21.

A bar magnet is equivalent to

• torroid carrying current

• straight conductor carrying current

• solenoid carrying curren

• circular coil carrying current

The electrons in the beam of a television tube move horizontally from South to North. The vertical component of the earth's magnetic field points down. The electron is deflected towards

• West

• no deflection

• East

• North to South

Among the followmg properties describing diamagnetism identify the property that is wrongly stated :

• Diamagnetic material do not have permanent magnetic moment

• Diamagnetism is explained in terms of electromagnetic induction

• Diamagnetic materials have a small positive susceptibility

• The magnetic moment of individual electrons neutralize each other

Ferromagnetic materials used in a transformer must have

• low permeability and high hysterisis loss

• high permeability and low hysterisis loss

• high permeability and high hysterisis loss

• low permeability and low hysterisis loss

A susceptibility of a certain magnetic material is 400. What is the class of the magnetic material ?

• Diamagnetic

• Paramagnetic

• Ferromagnetic

• Ferroelectric

Core of electromagnets are made of ferromagnetic material which has

• low permeability and high retentivity

• high permeability and low retentivity

• low permeability and low retentivity

• high permeability and high retentivity

An aircraft with a wingspan of 40 m flies with a speed of 1080 km/h in the Eastward direction at a constant altitude in the Northern  hemisphere, where the vertical component of the Earth's magnetic field is 1.75 × 10^-5 T. Then the emf developed between the tips of the wings is

• 0.21 V

• 0.5 V

• 2.1 V

• 0.34 V

The magnetic susceptibility of a paramagnetic material at -73°C is 0.0075 and its value at − 173°C will be

• 0.015

• 0.0045

• 0.0075

• 0.0030

${\mathrm{\chi }}_1$ and ${\mathrm{\chi }}_2$ are susceptibility of a paramagnetic material at temperatures T₁ K and T₂ K respectively, then

• ${\mathrm{\chi }}_1 = {\mathrm{\chi }}_2$

• ${\mathrm{\chi }}_1{\mathrm{T}}_1 = {\mathrm{\chi }}_2{\mathrm{T}}_2$

• ${\mathrm{\chi }}_1{\mathrm{T}}_2 = {\mathrm{\chi }}_1{\mathrm{T}}_1$

• ${\mathrm{\chi }}_1 \sqrt{{\mathrm{T}}_1} = {\mathrm{\chi }}_2 \sqrt{{\mathrm{T}}_2}$

At certain place, the horizontal component of Earth's magnetic field is 3.0 G and the angle dip at that place is 30°. The magnetic field of Earth at that location is

• 4.5 G

• 5.1 G

• 3.5 G

• 6.0 G