Answer:
a) x= 1,118 10⁴ m, b) x= 3.7 104 m
Step-by-step explanation:
To calculate the decrease in intensity with depth, write the equation
I = I₀
Where Io is the intensity at the surface and alf is the absorption coefficient
Ln (I / I₀) = - α x
x = -1 /α ln (I / I₀)
Let's apply this expression to our case
a) intensity is half of the surface
I / I₀ = 0.5
We calculate
x = -1 /6.2 10⁻⁵ ln (0.5)
x = 0.1118 10⁵ m = 1,118 10⁴ m
b) the intensity is one tenth
I / Io = 0.1
x = -1 / 6.2 10⁵ ln (0.1)
x = 0.37138 10⁵ = 3.7 104 m