The given diagram exhibits the relationship between the wavelength of the electromagnetic waves and the energy of photon associated with them. The three points $\mathbf{P}, \mathbf{Q}$ and $\mathbf{R}$ marked on the diagram may correspond respectively to

The electromagnetic waves used to purify water are

$$\vec{E}$$ 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

Which one of the following electromagnetic radiation has the least wavelength?