What is the longest possible wavelength emitted in the Balmer series?
A 344 nm
B 365 nm
C 545 nm
D 656 nm
The correct answer and explanation is:
The correct answer is B: 365 nm.
The Balmer series refers to the set of spectral lines of hydrogen atoms that are visible to the human eye. These spectral lines are associated with transitions of an electron from higher energy levels to the second energy level (n=2). The wavelengths emitted in this series fall within the visible spectrum.
The longest wavelength emitted in the Balmer series occurs when the electron transitions from the third energy level (n=3) to the second energy level (n=2). This is the first line of the Balmer series, known as the H-alpha line, and its wavelength is around 656 nm, which is red in color.
However, the longest wavelength in the series is not the H-alpha line itself, but the transition corresponding to the limit of the Balmer series. This transition happens when the electron drops from an infinitely high energy level (n=∞) to the second energy level (n=2). The wavelength of this limit corresponds to the 364.506 nm mark, which is close to 365 nm.
This wavelength is the longest in the Balmer series because it represents the lowest energy transition that still results in an emitted photon within the visible spectrum. As the transition involves higher energy levels, the wavelength decreases, which is why shorter wavelengths correspond to transitions involving higher levels (such as n=4 to n=2, etc.).
Thus, 365 nm is the longest possible wavelength emitted in the Balmer series, corresponding to the transition from n=∞ to n=2, just before moving into the ultraviolet range.