Explanation of Lyman Series:
The Lyman series is a series of spectral lines in the ultraviolet region of the hydrogen spectrum. These lines are emitted when an electron transitions from a higher energy level to the ground state (n=1) in a hydrogen atom.

Calculating the Ratio:
To find the ratio of the highest possible wavelength to the lowest possible wavelength in the Lyman series, we need to consider the energy levels involved in the transitions. The Lyman series starts from the n=2 energy level and goes up to infinity.
- The highest possible wavelength in the Lyman series corresponds to the transition from n=∞ to n=2.
- The lowest possible wavelength in the Lyman series corresponds to the transition from n=2 to n=1.

Using the Rydberg formula:
The formula for calculating the wavelength of a spectral line in the hydrogen spectrum is given by the Rydberg formula:
1/λ = R (1/n1^2 - 1/n2^2)
Where λ is the wavelength, R is the Rydberg constant, and n1, n2 are the initial and final energy levels.
- For the highest possible wavelength (n=∞ to n=2), we substitute n1=2, n2=∞ into the formula.
- For the lowest possible wavelength (n=2 to n=1), we substitute n1=1, n2=2 into the formula.

Calculating the Ratio:
Once we have the wavelengths for the highest and lowest transitions, we can simply take the ratio of the two values to find the ratio of the highest possible wavelength to the lowest possible wavelength in the Lyman series.
This ratio gives us an idea of the spread of wavelengths in the Lyman series and helps in understanding the energy levels involved in the transitions.