Critical angle may refer to:
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Critical angle (optics)
Total internal reflection (TIR) is the optical phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected b ...
, the angle of incidence above which total internal reflection occurs
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Critical angle of attack
In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is mo ...
, in aerodynamics; the angle of attack which produces the maximum lift coefficient
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Critical angle of repose, in engineering; the steepest angle of descent of a slope when the material is on the verge of sliding
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