Which term corresponds to the critical angle?

Which term corresponds to the critical angle?

• A. Crown height percentage
• B. Critical angle
• C. Cratons
• D. Covalent bond

Answer: (B)

The critical angle is the angle of incidence in a denser medium that makes the refracted ray skim along the boundary of the second medium, meaning the refracted angle is 90 degrees. This occurs because, by Snell’s law, n1 sin(theta_c) = n2 sin(90°) = n2, so sin(theta_c) = n2/n1 (which only makes sense when n1 > n2). When the incidence angle is smaller than this, light passes into the second medium and bends away from the normal; when it is larger, total internal reflection occurs and no refracted ray enters the second medium. The other terms listed belong to fields outside optics, such as dentistry, geology, or chemistry, so they do not describe this optical concept.

The critical angle is the angle of incidence in a denser medium that makes the refracted ray skim along the boundary of the second medium, meaning the refracted angle is 90 degrees. This occurs because, by Snell’s law, n1 sin(theta_c) = n2 sin(90°) = n2, so sin(theta_c) = n2/n1 (which only makes sense when n1 > n2). When the incidence angle is smaller than this, light passes into the second medium and bends away from the normal; when it is larger, total internal reflection occurs and no refracted ray enters the second medium. The other terms listed belong to fields outside optics, such as dentistry, geology, or chemistry, so they do not describe this optical concept.