Light from a laser enters a glass block at A and emerges at B; see the figure. The glass block has a length and an index of refraction . The angle of incidence is . We have to find the time needed for light to pass through the block.
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Solution: Click For PDF Version The length of the glass block, .The index of refraction of the glass, . The angle of incidence of the laser beam, . Therefore, the angle of refraction of the laser beam inside the glass block can be determined from the Snell’s law,
The path length of the laser beam inside the glass block will therefore be
The speed of light inside the glass block will be
Therefore, the time needed for the light to pass through the block will be
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