Total Internal Reflection and Critical Angle Quiz

What is the critical angle?

• The angle of incidence for which the angle of refraction in the less optically dense medium is 90°.

• The angle at which light is absorbed by a medium.

• The angle at which light passes straight through a medium.

• The angle at which light is scattered in all directions.

What happens to a ray of light as it passes from a more dense to a less dense medium?

• It bends away from the normal.

• It bends toward the normal.

• It is absorbed by the medium.

• It passes straight through without bending.

Why does the refracted ray bend away from the normal when light passes from water to air?

• Because air is less optically dense than water.

• Because air is more optically dense than water.

• Because water absorbs the light.

• Because the angle of incidence is always zero.

What is the critical angle for a light ray passing from light flint glass (n = 1.58) to water (n = 1.33)?

• 39.3°

• 57.3°

• 42.0°

• 90.0°

Which formula is used to calculate the critical angle when the less dense medium is air?

• sinθc = n₂ / n₁

• sinθc = n₁ / n₂

• sinθc = n₁ × n₂

• sinθc = n₂ - n₁

What phenomenon is demonstrated when a green laser beam in a fish tank reflects off the underside of the water surface instead of escaping into the air?

• Refraction

• Diffraction

• Total internal reflection

• Dispersion

Why does no refraction occur at the first surface when a ray enters a semicircular glass block along a radius?

• The surface is rough

• The ray is perpendicular to the surface

• The glass is opaque

• The light is absorbed

How does an optical fibre transmit a light signal over long distances with a low loss of energy?

• By using mirrors to reflect the light inside the fibre.

• By allowing the light to escape at each bend.

• By using total internal reflection to keep the light inside the fibre.

• By absorbing the light and re-emitting it at the other end.

Which of the following pairs of media can allow total internal reflection to occur?

• Air to glass

• Water to glass

• Diamond to air

• Crown glass to perspex

Students investigating total internal reflection using a semicircular block of glass notice a faint reflected beam before total internal reflection occurs. What happens to the intensity of the reflected beam as the angle of incidence increases?

• The intensity decreases.

• The intensity remains the same.

• The intensity increases until total internal reflection occurs.

• The intensity disappears immediately.