School of Physics Lecture Demonstration Manual

Of-4 Absorption Spectrum of Sodium

Published: Wednesday 15 March 2006 - Updated: Monday 28 March 2011

Aim

To demonstrate that sodium vapour absorbs strongly at a wavelength equal to its characteristic emission lines.

Apparatus

Diagrams

Click on pictures to enlarge.

Absorption of Sodium Diagram

Videos

Absorption lines of Sodium

Description

A wire coated in NaC1 is heated in a bunsen flame and placed directly in front of a sodium light source. The sodium vapour emanating from the heated wire is seen as a black mist due to its absorption of the source's characteristic wavelengths. This is clearly visible in a large classroom.

Safety notes

Electrical safety 

Fire/Burn safety 

Personal safety 

Maintenance 

top of page