- #1

TachyonLord

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## Homework Statement

In the Fizeau's Experiment to determine the speed of light, let the gear have

**N**teeth, the frequency of the rotating gear being

**f,**the distance traveled by the light beam/ray

**L**(distance b/w the gear and the mirror) and let there be

**n**eclipses(blocking of the light beam).

__Calculate the speed of light.__

More information on the experiment :

## Homework Equations

$$Speed =\frac {Distance} {Time}$$

$$ f = \frac 1 T$$

Angular frequency(w) = 2πf

## The Attempt at a Solution

So I tried solving this by using $$c(speed of light) = \frac {2L} t$$

where T will be the time for the light to pass through the teeth and then be reflected.If T is the time period of the gear, then $$t = \frac T {2N}$$

because I'm thinking that the time for one eclipse should be the time taken to go from A to B, which is equivalent to one tooth's length.

$$⇒ t = \frac {1} {2fN}$$

And subsequently,

**c = 4LfN**, but this doesn't include n.

So I tried a different approach and used the formula $$t = \frac d v$$

$$d = \frac {2πR} {2N}$$

v = (2πf)R

which again gives the same answer, without the

**n**term.

I also thought of another situation, where the light goes through the gap and is blocked by some tooth(which is not the successive one) which seems absurd in itself and I don't really know how to continue.

The answer that was annouced in the class had something like (2n-1) in the denominator. I don't know where I'm going wrong.

Thank you.

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