A body is projected vertically upwards from the surface of earth with a velocity ' $v$ ' to reach a height of $10 R$, where $R$ is the radius of the earth, then $v$ is
$\sqrt{\frac{21 \mathrm{gR}}{10}}$
$\sqrt{\frac{21 \mathrm{gR}}{11}}$
$\sqrt{\frac{20 \mathrm{gR}}{11}}$
$\sqrt{\frac{10 \mathrm{gR}}{11}}$
An AC generator having 400 turns and an area of cross section of $2 \times 10^{-3} \mathrm{~m}^2$ rotates with an angular speed of $200 \pi \mathrm{rad} \mathrm{s}^{-1}$ in a uniform magnetic field of strength 0.4 T . The generator is connected to the primary of an ideal transformer having 500 turns in the primary and 2000 turns in the secondary. The secondary is connected to a $400 \Omega$ resistive load. What is the rms current in the secondary of the transformer? Assume, the transformer is ideal and the resistance of the coil is negligible
2.84 A
14.2 A
1.41 A
28.4 A
An object of mass 10 g executes SHM along the $x$-axis with frequency of $\left(\frac{10}{\pi}\right) \mathrm{Hz}$. At the point $x=2 \mathrm{~cm}$ the object has KE 1.2 J and PE 0.4 J . The amplitude of oscillation is
8 cm
4 cm
2 cm
6 cm
A circular coil of radius 7 cm and 40 turns is rotated about its vertical diameter with an angular speed of 40 radians per second in a uniform horizontal magnetic field of $4 \times 10^{-2} T$. What is the maximum current induced in the coil if the resistance of the coil is $11 \Omega$ ?
90 mA
0.9 mA
9 mA
0.09 mA
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