When you look through a window, by how much time is the...

Name: Problem 25, Chapter 35: Physics for Scientists and Engineers with Modern Physics
Uploaded: 2020-09-12T20:04:44-08:00
Duration: 3 min 14 s
Channel: Aatish Gupta
Description: When you look through a window, by how much time is the light you see delayed by having to go through glass instead of air? Make an order-of-magnitude estimate on the basis of data you specify. By how many wavelengths is it delayed?

When you look through a window, by how much time is the light you see delayed by having to go through glass instead of air? Make an order-of-magnitude estimate on the basis of data you specify. By how many wavelengths is it delayed?

Key Concepts

Order-of-Magnitude Estimation

Order-of-magnitude estimation, often referred to as dimensional analysis or Fermi estimation, is a method used to quickly approximate values within a factor of ten. This approach simplifies complex calculations by focusing on the scale or magnitude of the numbers involved rather than precise values, making it particularly useful in problems where only an approximate answer is needed.

Propagation Delay

Propagation delay refers to the time difference in light’s travel when it passes through different media due to speed variations. This delay can be estimated by comparing the distance light travels in that medium with its reduced speed relative to air or vacuum, which is a key concept in optics and telecommunications.

Wavelength in a Medium

The wavelength of light in a medium is shorter than its wavelength in a vacuum by a factor equal to the index of refraction. This relationship is important when comparing the physical distance traveled by light to the number of wavelengths encompassed within that distance, and it plays a crucial role in interference and diffraction phenomena.

Index of Refraction

The index of refraction is a measure of how much a medium slows down light compared to its speed in a vacuum. It quantifies the change in speed and bending of the light's path as it enters a different medium. In most transparent solids like glass, the index is greater than 1, meaning light travels slower than in air or vacuum.

Speed of Light in a Medium

The speed of light in any medium is determined by dividing the speed of light in a vacuum by the medium's index of refraction. This reduction in speed is critical when calculating how long it takes light to traverse a particular distance within that medium, and it leads directly to time delays in transmission.

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