In a photoelectric experiment light of wavelength 800 nm produces photoelectrons with the smallest de-Broglie wavelength of 1 nm . Light of 400 nm produces photoelectrons with smallest de-Broglie wavelength of 0.5 nm. Then the work function of the metal used in the experiment is nearly.
A hydrogen atom at the ground level absorbs a photon and is excited n = 4 level. The potential energy of the electron in the excited state is
The radius of an atomic nucleus of mass number 64 is 4.8 fermi. Then the mass number of another atomic nucleus of radius 6 fermi is
Consider the statements In a semiconductor
(A) There are no free electrons at 0 K.
(B) There are no free electrons at any temperature.
(C) The number of free electrons increases with temperature.
(D) The number of free electrons is less than that in a conductor.