The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (kelvin) and mass m, is

The photoelectric threshold wavelength of silver is 3250 $$ \times $$ 10^$$-$$10 m. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 $$ \times $$ 10^$$-$$10 m is
{Given h = 4.14 $$ \times $$ 10^$$-$$15 eV s and c = 3 $$ \times $$ 10⁸ m s^$$-$$1 ]

The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is

Which one of the following represents forward bias diode ?