Consider a 400 nm thick film of water (n-1.33) on plastic (-1.9). visible light is incident. on the film firom air. (25 pts) sketch this situation and clearly indicate the rays which are interfering with one another. (5 pts) a b. find three wavelengths that will be reflected brightly from the film. (14 pts) c. find three wavelengths that will be reflected very dimly, if at all, from the film.

Explanation:

For constructive interference in thin films by reflected light , the condition is

Path difference =  2μd = odd multiple of λ / 2

Where μ is refractive index of water , d is thickness of water medium and λ

is wavelength of light

λ = 4μd or 4μd / 3 or 4μd / 5

= 4 x 1.33 x 400 nm = 2128 nm

or 2128 /3 = 709.33 nm

or 2128 /5 = 425.6 nm

For destructive interference ( dim reflection )

2μd = multiple of λ = λ or 2λ or 3λ

2 x 1.33 x 400 nm =1064

or 1064 x 2 = 2128 nm

or 1064 x 3 = 3192 nm.

carbon is found in all living things. carbon atoms move constantly through

living organisms, the oceans, the atmosphere, and the earth’s crust in what is

known as the carbon cycle. the directions taken by carbon atoms through this

cycle are very complicated and can take millions of years to make a full circle.

all animals, from humans to the dinosaurs are part of the carbon cycle. when

animals eat food, they get carbon in the form of carbohydrates and proteins.

in animals, oxygen combines with food in the cells to produce energy for daily

activity and then gives off carbon. the carbon combines with oxygen to form

carbon dioxide (co2) and is released back into the atmosphere as a waste

product when animals breathe and exhale.

from 145-65 million years ago, earth was much

hotter than today and covered with dense,

tropical swamp forests. the trees and other

plants were immense and

provided an endless supply of

food for the giant animals that

roamed the land. somewhere in

the air above one of these

forests, a lone carbon atom has joined

up with two oxygen atoms to form a molecule of co2.

the co2 molecule was sucked into the tiny holes (stomata) on the leaf of a

fern plant and joined with sunlight, chlorophyll and water to make food and

energy in the plant’s cells through photosynthesis. the oxygen (o2) from the

co2 molecule was sent back into the atmosphere; the carbon atom (c) was

detached and used to make a molecule of sugar.

if that carbon atom had been eaten instead, a totally

different situation would have developed. let’s say

that a giant plant-eating dinosaur (herbivore) ate the

fern for breakfast, and swallowed the carbon in the

fern in the form of carbohydrates and proteins. in

the process of respiration, oxygen combined with

the carbohydrates and proteins in the dinosaur’s cells

to provide energy for its daily activity.  

s the environmental science is a broader field that incorporates many elements of earth and life sciences, whereas ecology is usually more focused on how organisms interact with each other and their surroundings, and often on a very specific population of living things. soo yea

explanation: