What happens when a hydrogen atom absorbs a quantum of energy?

An object of dimensions 50 cm x 40 cm x 0.20 cm has a mass 60g. find its density in g/cm3 and kg/ m3

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.

** urgent** the voltage across the primary winding is 350,000 v, and the voltage across the secondary winding is 17,500 v. if the secondary winding has 600 coils, how many coils are in the primary winding? a- 30 coilsb- 583 coilsc- 12,000 coilsd- 332,500 coils