In a photoelectric experiment ultraviolet light of wavelength 280 nm is used with lithium cathode having work function $$\phi$$ = 2.5 eV. If the wavelength of incident light is switched to 400 nm, find out the change in the stopping potential. (h = 6.63 $$\times$$ 10^$$-$$34 Js, c = 3 $$\times$$ 10⁸ ms^$$-$$1)

In the given figure, the emf of the cell is 2.2 V and if internal resistance is 0.6$$\Omega$$. Calculate the power dissipated in the whole circuit :

A solid metal sphere of radius R having charge q is enclosed inside the concentric spherical shell of inner radius a and outer radius b as shown in the figure. The approximate variation electric field $$\overrightarrow E $$ as a function of distance r from centre O is given by

The rms speeds of the molecules of Hydrogen, Oxygen and Carbon dioxide at the same temperature are V_H, V_O and V_C respectively then :