Notes of Chapter 09: Nature of Light of “Physics XI” for FSc Part 1 published by Sindh Textbook Board, Jamshoro. These notes are very helpful to prepare Physics paper of FSc Part 1 for Sindh Board. These can also be consider as refrence notes for Federal Board, Multan Board, Faisalabad Board, Sargodha Board, Gujranwala Board, DG Khan Board, Rawalpindi Board or any other board of Pakistan.

Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in vacuum. In common with all types of EMR, visible light is emitted and absorbed in tiny “packets” called photons …