Power = (energy) divided by (time)
<span> we suppose that x be distance of man from spot light is
so 12-x is distance from man to wall
we will draw first triangle ABC, where
a= spotlight (on ground)
b= man (feet)
c= man (head)
we know that AB = x and BC = 2
by extend line AB to the wall at point D and extend line AC to the wall at point E
AD = 12 (distance from spotlight to wall)
DE = s (length of shadow)
Now triangles ABC and ADE are similar
Therefore DE/AD = BC/AB
s / 12 = 2 / x
s = 24 / x
Differentiate both sides with respect to t
ds/dt = -24/x² dx/dt
Man is walking toward building at speed of 16 ms
dx/dt = 16
Man is 4 m from the building/wall
12 - x = 4
x = 8
Find ds/dt when x = 8 and dx/dt = 16
ds/dt = -24/x² dx/dt
ds/dt = -24/(64) * 16
ds/dt = -6
So length of shadow is decreasing at rate of 6 m/s
hope it helps
</span>
La capital de Puerto Rico es la ciudad "San Juan".
Answer:
t = 200 nm
Explanation:
It is given that,
Wavelength of a light beam is 500 nm
It is reflected constructively from a thin layer of oil having index of refraction 1.25.
The oil floats on the top of water of index of refraction 1.33.
We need to find the minimum thickness of the layer of oil. `
For constructive interference,
m is 1 for minimum thickness
n is refractive index of oil
t is thickness of layer of oil.
So,
So, the minimum thickness of the layer of oil is 200 nm.
