critical angle

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Related to critical angles: Total internal reflection

critical angle:

see refractionrefraction,
in physics, deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different, as the passage of a light ray from air into glass.
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critical angle

[′krid·ə·kəl ¦aŋ·gəl]
(architecture)
The angle of pitch of a flight of stairs or a ramp that, if exceeded, is considered uncomfortable and unsafe; it is 50° for stairs and 20° for ramps.
(physics)
An angle associated with total reflection of electromagnetic or acoustic radiation back into a medium from the boundary with another medium in which the radiation has a higher phase velocity; it is the smallest angle with the normal to the boundary at which total reflection occurs.

critical angle

An angle of pitch of stairs or a ramp which is considered uncomfortable and unsafe if exceeded; this angle is 50° for stairs and 20° for ramps.

critical angle

critical angle
If radio wave hits the ionosphere at an angle higher than critical angle, it would not be reflected back, but will pass through the ionosphere into space.
critical angle
critical angleclick for a larger image
i. The minimum angle of incidence at which a radio wave of a particular frequency can strike the ionosphere and still be reflected back to the earth. Critical angle is a function of frequency; the higher the frequency, the larger the critical angle.
ii. The angle of attack of an airfoil at which the flow of air about the airfoil changes abruptly in such a manner that the lift is sharply reduced and the drag is sharply increased. Sometimes called stalling angle of attack.
iii. The angle at which a reflected ray of light when transmitted from a denser to a rarer medium is bent so far from the normal that it does not enter the rarer medium at all but travels parallel to the surface between the media.
iv. The angle of bank beyond which a helicopter resting on the ground on one skid or one wheel is likely to roll over in an uncontrolled manner.
At the instant of rollover of a helicopter, a moment is produced by the horizontal component of total rotor thrust about the point of ground contact of the skid. This moment is opposed by weight of the aircraft. If the angle of bank is beyond the critical angle the restoring moment is too small to stop the helicopter from rolling over.

critical angle

In an optical fiber, the maximum angle from the axis at which light can remain confined within the core for "total internal reflection." In contrast to the "acceptance angle," which is measured outside the fiber, the critical angle is a measurement within the fiber. See numerical aperture.
References in periodicals archive ?
Figure 5 presents the dependence [bar.[i.sub.0]] = f([bar.i']), the analysis of which demonstrates that hysteresis by critical angle of attack occurs in different values of inability to calculate the flow at [bar.i'] > 1.
Table 1 lists many branch points [[delta].sup.-.sub.n] together with their corresponding critical angles [[theta].sup.-.sub.n].
E-mail: bmccarti@kettering.edu Table 1: Branch Points and Critical Angles n [[delta].sup.-.sub.n] [[theta].sup.-.sub.n] 0 2.106196+1.125364[??] .7150[pi] 1 2.178042+1.384339[??] .6500[pi] 2 2.214676+1.551574[??] .6172[pi] 3 2.237591+1.676105[??] .5970[pi] 4 2.253497+1.775544[??] .5832[pi] 5 2.265277+1.858384[??] .5730[pi] 6 2.274400+1.929404[??] .5653[pi] 7 2.281699+1.991571[??] .5591[pi] 8 2.287689+2.046852[??] .5541[pi] 9 2.292704+2.096626[??] .5499[pi] 10 2.296970+2.141891[??] .5464[pi] 100 2.346069+3.229037[??] .5074[pi] 1,000 2.354804+4.373567[??] .5010[pi] 10,000 2.356019+5.524184[??] .5001[pi]
For modes n = 0 and n = 1, there is a critical angle [[theta].sup.-.sub.n] such that for [theta] < [[theta].sup.-.sub.n] we have the mode morphing [N.sub.n](x) [??] [D.sub.n+1](x) while, for [theta] > [[theta].sup.-.sub.n], mode n is missing in the previously defined sense as r [right arrow] 1.
As these parameters one can consider, in the first instance, the already mentioned analytical form of the influence functions and also the value of the critical angle of influence (Neset, 1984), which is approximately 60[degrees] to 65[degrees] under the mining and geological conditions of the Kladno District (Lucak, 1968).
Figure 6 and the values of the differences between the actual and theoretical subsidence of all points involved, listed in Appendix 3 (Columns 5 through 11) clearly show that the model with the Bals influence function, provided the critical angle is considered in the range of 56-58[degrees], is again the most suitable theoretical model of the undermining effects.
3 Finite planar measurement area and corresponding critical angles.
Having established these critical angles of vision, Brooker is able to pursue their specific realizations.
Confirming Casa's status as one of the most complex and interesting writers of the Italian Cinquecento, the value of these essays is enhanced not only by the depth of scholarship brought to bear on the individual works, from textual, linguistic, and critical angles, but also by their breadth of reference to Casa's corpus as a whole, to his numerous and sometimes recondite sources, and not least to the cultural and political context in which his works were produced, read and edited.

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