Why are infra-red waves often called heat waves? Explain.

An alpha nucleus of energy 1 /2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to 

If I₀ is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity when the slit width is doubled?

The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young’s double-slit experiment is

According to Einstein’s photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Vs the frequency, of the incident radiation gives straight line whose slope