(a) (i) What are matter waves ? A particle of mass m and charge q is accelerated from rest through a potential difference V. Obtain an expression for de Broglie wavelength associated with the particle. (ii) Monochromatic light of frequency $5.0 \times 10^{14} \text{ Hz}$ is produced by a source of power output $3.315 \text{ mW}$. Calculate : (1) energy of the photon in the beam (2) number of photons emitted per second by the source OR (b) (i) State Bohr's postulates and derive an expression for the energy of electron in $\text{n}^{\text{th}}$ orbit in Bohr's model of hydrogen atom. (ii) Calculate binding energy per nucleon (in $\text{MeV}$) of $_{6}^{12}\text{C}$. Given : $m(_{6}^{12}\text{C}) = 12.000000 \text{ u}$ $m(_{0}^{1}\text{n}) = 1.008665 \text{ u}$ $m(_{1}^{1}\text{H}) = 1.007825 \text{ u}$