A box of mass $$5 \mathrm{~kg}$$ is pulled by a cord, up along a frictionless plane inclined at $$30^{\circ}$$ with the horizontal. The tension in the cord is $$30 \mathrm{~N}$$. The acceleration of the box is (Take $$g=10 \mathrm{~m} \mathrm{~s}^{-2}$$)
If the ratio of relative permeability and relative permittivity of a uniform medium is $$1: 4$$. The ratio of the magnitudes of electric field intensity $$(E)$$ to the magnetic field intensity $$(H)$$ of an EM wave propagating in that medium is (Given that $$\sqrt{\frac{\mu_0}{\varepsilon_0}}=120 \pi$$):
The value of electric potential at a distance of $$9 \mathrm{~cm}$$ from the point charge $$4 \times 10^{-7} \mathrm{C}$$ is [Given $$\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9 \mathrm{~N} \mathrm{~m}^2 \mathrm{C}^{-2}$$] :
The displacement of a travelling wave $$y=C \sin \frac{2 \pi}{\lambda}$$ (at $$-x$$) where $$t$$ is time, $$x$$ is distance and $$\lambda$$ is the wavelength, all in S.I. units. Then the frequency of the wave is