An excited hydrogen atom has an electron in its n = 4 energy level. The electron subsequently drops down to the n = 2 level, emitting a photon. a. What is the wavelength AND type of light (IR, Visible, etc.) emitted by this transition?
b. What is the frequency of the emitted photon?
c. What is the energy of the emitted photon?

Butterfly wingspan is 7.7

Following are the  advantages of the parametric equations: 1) they can be used to graph curves that are not functions, like the unit circle.2) the parameter can be used to represent the quantity that is  useful to  provide us with better information about the graph.3)  it is useful to convert between rectangular equations and parametric equations.with specific reference to chemistry,  parametric equations are employ for solving hydrogen and hydrogen-like ions, quantum mechanically. herein, cartesian coordinates are converted in spherical polar coordinates. the solution obtained, when plotted on spherical polar graph paper, provides visualization of atomic orbital such as s,p,d and f. 

Provide more information for : )