Two metal spheres, one of radius $$\frac{R}{2}$$ and the other of radius $$2 \mathrm{R}$$ respectively have the same surface charge density They are brought in contact and separated. The ratio of their new surface charge densities is
Find the value of '$$n$$' in the given equation $$P=\rho^n v^2$$ where '$$P$$' is the pressure, '$$\rho$$' density and '$$v$$' velocity.
A stone of mass $$2 \mathrm{~kg}$$ is hung from the ceiling of the room using two strings. If the strings make an angle $$60^{\circ}$$ and $$30^{\circ}$$ respectively with the horizontal surface of the roof then the tension on the longer string is : $$g=10 \mathrm{~ms}^{-2}$$
A parallel plate capacitor is filled by a dielectric whose relative permittivity varies with the applied voltage (U) as $$\epsilon=2 U$$. A similar capacitor with no dielectric is charged to $$U_0=78 \mathrm{~V}$$. It is then connected to the uncharged capacitor with the dielectric. Find the final voltage on the capacitors.