1 critical angle | Definition of critical angle

critical angle

noun

Definition of critical angle

: the least angle of incidence at which total reflection takes place

Illustration of critical angle

Illustration of critical angle

critical angle: AOB, AO'B', AO''B'' angles of incidence; AOC refracted ray; AO''C'' totally reflected ray; AO'B' critical angle

First Known Use of critical angle

1873, in the meaning defined above

Keep scrolling for more

More from Merriam-Webster on critical angle

Britannica.com: Encyclopedia article about critical angle