A long straight wire of radius '$$a$$' carries a steady current $$I$$. The current is uniformly distributed across its area of cross-section. The ratio of magnitude of magnetic field $$\vec{B}_1$$ at $$\frac{a}{2}$$ and $$\vec{B}_2$$ at distance $$2 a$$ is

$$\vec{E}$$ and $$\vec{B}$$ represent the electric and the magnetic field of an electro- magnetic wave respectively. The direction of propagation of the wave is along

A ray of monochromatic light propagating in air, is incident on the surface of water. Which of the following will be the same for the reflected and refracted rays?

A beam of light travels from air into a medium. Its speed and wavelength in the medium are $$1.5 \times 10^8\mathrm{ms}^{-1}$$ and $$230 \mathrm{~nm}$$ respectively. The wavelength of light in air will be