$$\epsilon_0$$ and $$\mu_0$$ are the electric permittivity and magnetic permeability of free space respectively. If the corresponding quantities of a medium are $$2 ~\epsilon_0$$ and $$1.5 ~\mu_0$$ respectively, the refractive index of the medium will nearly be :
The amount of elastic potential energy per unit volume (in SI unit) of a steel wire of length $$100 \mathrm{~cm}$$ to stretch it by $$1 \mathrm{~mm}$$ is (if Young's modulus of the wire $$=2.0 \times 10^{11} \mathrm{Nm}^{-2}$$ ) :
The $$4^{\text {th }}$$ overtone of a closed organ pipe is same as that of $$3^{\text {rd }}$$ overtone of an open pipe. The ratio of the length of the closed pipe to the length of the open pipe is :
A long straight wire of length $$2 \mathrm{~m}$$ and mass $$250 \mathrm{~g}$$ is suspended horizontally in a uniform horizontal magnetic field of $$0.7 \mathrm{~T}$$. The amount of current flowing through the wire will be $$\left(\mathrm{g}=9.8 \mathrm{~ms}^{-2}\right)$$ :