Class 12th

Yes, whether a wave is coherent or incoherent depends on its phase difference and frequency. For converting a coherent wave into an incoherent wave, you have to damage the stable phase of the wave. This can be done by making the medium tough or mixing them with incoherent waves.

Similarly, incoherent waves can be converted into coherent waves by making their frequencies same and having all of them into the same phase.

Photocell works on photoelectric effect.

X_C  = 1/ ωC

On increasing w; XC decreases so Z decreases, current in circuit increases.

Yes, it strongly depends on the wavelength of the light wave. It is directly proportional to the length i.e. longer the wavelength, more will be the amount of diffraction. Similarly, short wavelength of the light will mean less diffraction comparatively.

Reflection is the concept of bouncing back of light waves when passed through a surface. Whereas, diffraction is a term used when light waves spread in different directions on being passed through an obstacle. Reflection requires a smooth surface whereas diffraction requires the edge of an object.

Interference is a concept that forms the base of diffraction, without which diffraction is not practically possible. The waves formed by diffraction form secondary waves which either cross each other, move in directions opposite to each other, or overlap each other. This situation creates some alternating bright and dark fringes called interference.

Nice Question! In this case, the matter wouldn't even exist. Atoms will exhibit non-uniform energy levels and can easily jump between different orbitals, leading to instability in the energies. This will lead to an unstable spectra and anything would, ;t exist today in the way we know it to be.

Linear momentum refers to the motion in a straight line, from one point to another. And angular momentum is the rotational equivalent of linear momentum. Since the electrons move in circular tracks or orbitals, the angular momentum is used to calculate the movement of these electrons.