Ascientist notices that an oil slick floating on water when viewed from above has many different rainbow colors reflecting off the surface. she aims a spectrometer at a particular spot and measures the wavelength to be 750 nm (in air). the index of refraction of water is 1.33.

part a: the index of refraction of the oil is 1.20. what is the minimum thickness of the oil slick at that spot? t= 313nm

part b: suppose the oil had an index of refraction of 1.50. what would the minimum thickness be now? t=125nm

i only need with part c. i put this in incase you need the information.

part c: now assume that the oil had a thickness of 200 nm and an index of refraction of 1.5. a diver swimming underneath the oil slick is looking at the same spot as the scientist with the spectromenter. what is the longest wavelength of the light in water that is transmitted most easily to the diver?

Explanation:

In case of oil slick a thin layer of oil is formed on water . This thin layer creates a rainbow of colour . The phenomenon is due to interference of light waves , one reflected from the upper surface of oil and the other reflected from the lower surface of the oil.

For formation of bright colour

2 μ t = ( 2n + 1 ) λ / 2

μ is refractive index of oil ,  t is thickness of oil layer  λ is wave length of light falling on the layer .

given μ = 1.2 ,   λ = 750 x 10⁻⁹   ,

2 x 1.2 t = ( 2n + 1 ) 750 x 10⁻⁹ / 2

For minimum thickness n = 0

2.4 t = 375 x 10⁻⁹

t = 156.25 n m

B ) If the refractive index of layer of medium below oil is less than that of oil , the condition of formation of colour changes

The new condition is

2 μ t = n λ

2  x 1.5 t  = 750 nm ,         n = 1 for minimum wavelength .

t = 250 nm

C ) Light mostly transmitted means dark spot is formed at that point .

For that to be observed from water side , the condition is

2 μ t = ( 2n + 1 ) λ / 2

λ = 4μ t / ( 2n + 1 )

For maximum wavelength n = 0

λ = 4μ t

= 4 x 1.5 x 200 nm

= 1200 nm .

what type of charge does it have? negative

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.