Light passes from air into flint glass at a nonzero angle of...

Name: Problem 18, Chapter 35: Physics for Scientists and Engineers with Modern Physics
Uploaded: 2020-06-06T07:51:22-08:00
Duration: 7 min 12 s
Channel: Zulfiqar Ali
Description: Light passes from air into flint glass at a nonzero angle of incidence. (a) Is it possible for the component of its velocity perpendicular to the interface to remain constant? Explain your answer. (b) What If? Can the component of velocity parallel to the interface remain constant during refraction? Explain your answer.

Light passes from air into flint glass at a nonzero angle of incidence. (a) Is it possible for the component of its velocity perpendicular to the interface to remain constant? Explain your answer. (b) What If? Can the component of velocity parallel to the interface remain constant during refraction? Explain your answer.

Key Concepts

Index of Refraction

This concept defines how much the speed of light is reduced in a medium compared to vacuum. It is given by n = c/v, where c is the speed of light in vacuum and v is the speed in the medium. Differences in the index of refraction between air and glass mean that light travels at different speeds in these materials, which is a key factor in understanding how its velocity components change during refraction.

Snell's Law

Snell's Law relates the sine of the angles of incidence and refraction to the indices of refraction of the two media through the equation n? sin(??) = n? sin(??). This law explains how and why the direction of light changes at the interface between different media, affecting the distribution of light's velocity into parallel and perpendicular components relative to the interface.

Decomposition of Velocity Components

When analyzing light refraction at an interface, its velocity is often resolved into components parallel and perpendicular to the interface. The perpendicular component is affected by the change in the actual speed of light between media, while the parallel component is influenced by the requirement that the wave's phase must match across the boundary.

Boundary Conditions and Conservation of the Parallel Component

Maxwell's equations impose continuity conditions at the interface between two media, ensuring that the parallel component of the wave vector (and consequently the parallel component of velocity) remains constant across the boundary. This directly explains why, despite changes in overall speed, the parallel component does not change during refraction.

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