A stationary wave is formed having 3 nodes along the length of the string 90 cm . The wavelength of the wave is

The spectral series observed for hydrogen atom found in visible region is

Three liquids of densities $\rho_1, \rho_2$ and $\rho_3$ (with $\rho_1>\rho_2>\rho_3$ ) having same value of surface tension T , rise to the same height in three identical capillaries. Angle of contact $\theta_1, \theta_2$ and $\theta_3$ respectively obey

The following figures show the variation of displacement with time of a particular object.