Question 4: What will be the wave number (v) of the spectral line of an electron when it jumps from n2 = 4 to n1 = 2?
Theory: Wave number is defined as the number of waves per unit length. It is equal to the reciprocal of the wavelength of the wave.
When an electron absorbs energy from some external source, it jumps up to some higher energy level. However, it remains there for some time and emits the same quantity of energy in the form of electromagnetic radiation falling back to the more stable lower energy state.
The relation of wave number is given as;
Here, R is Rydberg constant = 1.0974 × 107 m-1,
n1 is the number of lower orbit where the electron transits after emitting energy photon.
n2 is the number of higher orbit from where the electron jumps back.
Now put these values in the above equation,