Name two series of hydrogen spectrum lying in the infra red region.

Explanation

To answer the question regarding the two series of the hydrogen spectrum that lie in the infrared region, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Hydrogen Spectrum**: The hydrogen spectrum arises from the transitions of electrons between different energy levels (orbits) in a hydrogen atom. When an electron transitions from a higher energy level to a lower energy level, it emits light of a specific wavelength.

2. **Identifying Regions of the Spectrum**: The electromagnetic spectrum is divided into various regions based on wavelength:
- Infrared (IR) region: Wavelengths from about 700 nm (0.7 µm) to 1 mm.
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