The stopping potential for photoelectrons emitted from a surface illuminated by light of wavelength of 4910Angstrom is 0.71Angstrom is 0.71V.when the incident wavelength is changed the stopping potential is found 1.43V.what is wavelength?

A 4.00-g particle confined to a box of length L has a speed of 1.00 mm/s. (a) What is the classical kinetic energy of the particle? (b) If the energy of the first excited state (n = 2) is equal to the kinetic energy found in part (a), what is the value of L? (c) Is the result found in part (b) realistic? Explain.