CBSE Class 12-science Answered

Dear Student

I you send a laser through gap between cogs of the weel and tying to see teh laser reflection through the same gap.  At a particular speed of revoluyion , when the reflected light came to the wheel moves by a distance equals to the half of og separation so that yuo can not see teh reflection.

Time taken for the wheel to make one revoluition =   1/n   sec

Time taken for the wheel to move one cog separation = 1/(nm)   s

Time taken for the wheel to move one half of  cog separation = 1/(2nm)   sec-----(1)

Time taken for the light to reach the wheel= 2d/c-----(2)

Equationa (1),(2)  are equal  ===>  2d/c =1/(2  nm)  ==>  c= 4mnd

Regards

Team

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