Calculate the number of photon emitted in 10 hours by a 60 W sodium lamp (lemda or photon = 5893 A")

Calculate the longest wavelength which can remove the electron from first Bohrs orbit. Given E1 = 13.6 eV .

Calculate momentum of radiations of wavelength 0.33 nm.

The ionization energy of He+ is 19.6 10^-18 J atom^-1. The energy of the first stationary state of Li+2 will be :

Show that the wavelength of a 150 g rubber ball moving with a velocity 50 m sec^-1 is short enough to be observed ..