The transmission angle will be less than the incident angle when the speed of Medium 2 is ______ the speed of Medium 1.

The transmission angle will be less than the incident angle when the speed of Medium 2 is ______ the speed of Medium 1.

• A. Cannot determine
• B. Greater than
• C. Equal to
• D. Less than

Answer: (D)

When light passes from one medium into another, its speed changes and the path bends. If the second medium is slower, the wave slows down more after crossing the boundary, causing it to bend toward the normal and the transmission angle to become smaller than the incident angle. This ties to the refractive-index relationship: slower second medium means a higher index, so Snell’s law in effect makes sin of the transmitted angle smaller, giving a smaller angle. If the second medium had the same speed, the angles would be equal; if it were faster, the transmitted angle would be larger.

When light passes from one medium into another, its speed changes and the path bends. If the second medium is slower, the wave slows down more after crossing the boundary, causing it to bend toward the normal and the transmission angle to become smaller than the incident angle. This ties to the refractive-index relationship: slower second medium means a higher index, so Snell’s law in effect makes sin of the transmitted angle smaller, giving a smaller angle. If the second medium had the same speed, the angles would be equal; if it were faster, the transmitted angle would be larger.