A pith ball of mass ' $m$ ' gram and charge ' $Q$ ' is suspended using a mass less silk thread near a large charged conducting metal sheet of area ' $A$ ' and surface charged density ' $\sigma$ '. If the silk thread makes an angle $\Theta$ with the metal sheet, then:
$\tan \theta \propto \sigma$
$\tan \theta \propto A$
$\tan \theta \propto m g$
$\tan \theta \propto \frac{1}{\sigma}$
The material selected for making a permanent magnet should have:
High coercivity, low permeability and high retentivity
Low coercivity, low permeability and low retentivity
Low coercivity, low permeability and high retentivity
High coercivity, high permeability and high retentivity
Calculate the vapour pressure that can help the formation of a spherical droplet of water of radius $6.25 \times 10^{-5} \mathrm{~m}$ at $22^{\circ} \mathrm{C}$. Given: The surface tension of water at the given temperature is $7.28 \times 10^{-2} \mathrm{Nm}^{-1}$.
$1.01 \times 10^5 \mathrm{~Pa}$
$2.33 \times 10^3 \mathrm{~Pa}$
$8.81 \times 10^3 \mathrm{~Pa}$
$6.64 \times 10^4 \mathrm{~Pa}$
The atomic mass of an element $10 X^{20}$ is 19.98170 amu. The binding energy per nucleon of that element is: [given mass of neutron = 1.00867amu and mass of proton = 1.00783 amu and 1amu = 931 MeV ]
$17.66 \mathrm{MeV} /$ nucleon
$ 8.533 MeV /$ nucleon
$85.33 \mathrm{MeV} /$ nucleon
$170.66 \mathrm{MeV} /$ nucleon
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