A researcher measures the thickness of a layer of benzene (n = 1.50) floating on water by shining monochromatic light onto the film and varying the wavelength of the light. she finds that light of wavelength 600 nm is reflected most strongly from the film. part a what does she calculate for the minimum thickness of the film? express your answer with the appropriate units.

Explanation:

This problem relates to interference of light in thin films .

The condition of bright fringe in thin films which is sandwitched by two layers of medium having lesser refractive index  is as follows.

2nt = (2n+1) λ / 2  , n is refractive index of thin layer , t is its thickness ,  λ is wavelength of light .

2 x 1.5 t = λ / 2 , if n = 0 for minimum thickness.

2 x 1.5 t = 600 / 2 nm

t = 100 nm .

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it

because growing process had stoped after 4-5 year