An oil rig explosion in the Gulf of Mexico released tons of oil into the water. The narrator was hired to determine how much oil was spilled by measuring the thickness of the oil layer on top of the water. Their helicopter observed a strong blue reflection over an area of 50km by 10km. Using physics equations for thin film interference and properties of oil and blue light's wavelength, the narrator calculated the oil layer thickness as 408 nanometers. Factoring in the surface area, the total volume of spilled oil was determined to be 20 cubic meters.

1. Learning Object LO9
Thin film interference: Oil spill!
Question:
In the gulf an oilrig exploded releases tonnes of oil into the Gulf of Mexico. As
the oil diffuses across the gulf you are hired to determine how much oil has been
leaked into the ocean. To determine this you must figure out how thick the layer of
oil is on top of the water. You and your team ride a helicopter over the gulf and see a
strong blue reflection coming off the oil over an area of 50km by 10km!. You
suddenly realize that you took physics 101 and know how to determine how thick
the oil is! You know that blue light is approximately 453nm long and on average, oil
has an index of refraction of 1.11! How much oil was spilt!
A) 10000m^3
B) 2000m^3
C) 20m^3
D) 1500m^3
Solution:
ANS= C
- Since we have constructive interference happening we know to use the
constructive interference equation! Lambda=(2nt)/(m+1/2)
o N= index of refraction= 1.11
o T= length of film=?
o M= integer greater than 0=0
o Lambda= Wavelength of reflected light= 453nm
- Plug in the values!
o 453nm= (2*1.11*t)/(1/2)
o 906nm=(2*1.11*t)
o 408.108nm Thick!
- Now we can determine acutally how much oil has been spilt assuming that
the oil has spread evenly
- Volume of oil split= L*W*H spilt
o Volume= 50000m*10000m*408*10^-9m
o Volume split= 20m^3 barely anything!
- surprising?
BY: Taij Taggar