11.It kinetic energy of the emitted electted electrons is zero for the incident light of wavelength 686 nm. Then wavelength of radiations emitting electrons having energy 1.81 eV will be (Given : work function of cesium = 1.81 eV)

12.Charge on a stationary oil drop in Millikan s experiment is ne. Potential difference between the plates is 400 volts. If mass of the drop is doubled without changing the charge, then potential drop required to keep the drop stationary is

13.Photon A has twice the wavelength of photon B, then energy of photon A is

14.Work function of aluminium is 4.2 eV. If two photons each of energy 3.5 eV strike an electron of aluminum, then emission of electron

15.When a monochromatic point source of light is at a distance of 0.2 m from photoelectric cell, the cut-off voltage and the saturation current are 0.6 V and 18.0 mA respectively. If the same source is placed 0.6 m away from the photo cell, then