Q. Illustrates the branches of physics?
Answer:-
The basic branches of physics are classical mechanics electromagnetism including thermodynamics, optics, relativity and quantum mechanics.
Explain how was the length of a standard meter redefined in the year 1983?
Seeing as 1983 the meter has been defined as the distance light travels in a vacuum in exactly 1⁄ 299,792,458th of a second.