The first four spectral lines in the Lyman series of a H-atom are `lambda=1218Å, 1028Å,974.3Å and 951.4Å`. If instead of Hydrogen, we consider Deuterium, calculate the shift in the wavelength of these lines.

Explanation

To calculate the shift in the wavelengths of the first four spectral lines in the Lyman series of a hydrogen atom when considering deuterium instead, we will follow these steps:

### Step 1: Understand the Concept of Reduced Mass
The reduced mass (\( \mu \)) of a two-body system, such as an electron and a nucleus, is given by the formula:
\[ \mu = \frac{m_e \cdot m_N}{m_e + m_N} \]
where \( m_e \) is the mass of the electron and \( m_N \) is the mass of the nucleus (proton for hydrogen and deuteron for deuterium).
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