noun
critical angle
Technical term used in physics, optics, and engineering for the angle of incidence beyond which total internal reflection occurs, or more generally the angle at which a system becomes unstable.
光が水から空気へ進むとき、危険角度を超えると全反射が起こる。
When light travels from water to air, total reflection occurs if it exceeds the critical angle.
この斜面の危険角度は約30度で、それ以上だと土砂崩れの危険がある。
The critical angle of this slope is about 30 degrees; beyond that, there is a risk of landslide.
臨界角 is a more common synonym for 'critical angle' in physics, while 危険角度 is less frequent and may carry a nuance of danger or instability in broader contexts.
Compound of 危険 (danger, risk) and 角度 (angle). The term is a direct combination of these elements, likely a calque or technical coinage for 'critical angle'.