In an experiment with Foucault's apparatus, the various distances used are as follows :
Distance between the rotating and the fixed mirror = 16 m
Distance between the lens and the rotating mirror = 6 m,
Distance between the source and the lens = 2 m. When the mirror is rotated at a speed of 356 revolutions per second, the image shifts by 0.7 mm. Calculate the speed of light from these data.

Answer

A, B, D

Explanation

In the given Foucalt experiment
R= distance between fixed and rotating mirror =16 m
w=Angular speed = 356 rev/s `=356xx2pi rad/sec`
b=distance between lens and rotating mirror 6m
a=Distance between source and lens =2m
s=shift in image `=0.7m=0.7xx10^3m` So speed of light is given by
`c4R^2(wa)/(s(R+b))`
`=(4x(16)^2xx356xx2pixx2)/((0.7)xx10^-3(16+6))`
`=2.975xx10^8m/s`