In the mid-19th century, French physicist Foucault made the most accurate measurement of the speed of light using a laboratory-sized apparatus consisting of rotating and fixed mirrors. Consider a sour

Question

In the mid-19th century, French physicist Foucault made the most accurate measurement of the speed of light using a laboratory-sized apparatus consisting of rotating and fixed mirrors. Consider a source of light emitting a beam which bounces off a rotating mirror and then reflects off a small fixed mirror. By the time it reaches back to the rotating mirror, the mirror has rotated by a small angle. This rotation will deflect the beam through a small angle 30 minute of an arc from its original path. If the mirror rotates with a frequency $f ((5/3) \times 1 0^{4} Hz)$ and the speed of light is given as $3 \times 1 0^{8} m / sec$ , the value of D (where D is distance between rotating mirror and fixed mirror) is $\frac{5}{4} α m$ then the value of a is

Answer:

5

Solution:

Let frequency of rotating mirror be f .

$∴ \frac{2 D}{V} \times 2 π f = \frac{θ}{2} \Rightarrow D = \frac{25}{4} m$

TestHub · Accepted Answer

Let frequency of rotating mirror be f . ∴ V 2 D ​ × 2 π f = 2 θ ​ ⇒ D = 4 25 ​ m

Physics - Geometrical Optics Question with Solution | TestHub

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