Explain briefly Bohr's postulates. Using these postulates, derive an expression for wavelength of a radiation emitted in Hydrogen atom

Your target variable is δf, the magnitude of the difference in frequency between the waves emitted from the sonar device and the waves received by the device after reflecting off the whale. write an expression for δf in terms of the relevant frequencies using the subscript notation introduced above.

Two polarizers are oriented at 70∘∘ to one another. unpolarized light falls on them. what fraction of the light intensity is transmitted?

The air that we breath is made mostly of which gaseous molecule