The minimum energy required to launch a satellite of mass $$m$$ from the surface of earth of mass $$M$$ and radius $$R$$ in a circular orbit at an altitude of $$2 R$$ from the surface of the earth is:
A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to:
A. hold the sheet there if it is magnetic.
B. hold the sheet there if it is non-magnetic.
C. move the sheet away from the pole with uniform velocity if it is conducting.
D. move the sheet away from the pole with uniform velocity if it is both, non-conducting and non-polar.
Choose the correct statement(s) from the options given below:
A $$10 \mu \mathrm{F}$$ capacitor is connected to a $$210 \mathrm{~V}, 50 \mathrm{~Hz}$$ source as shown in figure. The peak current in the circuit is nearly $$(\pi=3.14)$$ :
A metallic bar of Young's modulus, $$0.5 \times 10^{11} \mathrm{~N} \mathrm{~m}^{-2}$$ and coefficient of linear thermal expansion $$10^{-5}{ }^{\circ} \mathrm{C}^{-1}$$, length $$1 \mathrm{~m}$$ and area of cross-section $$10^{-3} \mathrm{~m}^2$$ is heated from $$0^{\circ} \mathrm{C}$$ to $$100^{\circ} \mathrm{C}$$ without expansion or bending. The compressive force developed in it is :