Answer:
Explanation:
On both sides of the film , the mediums have lower refractive index.
for interfering pattern from above , for constructive interference of reflected wave from both sides of the film , the condition is
2μt = ( 2n +1 ) λ / 2
μ is refractive index of film ,t is thickness of film λ is wavelength of light
n is order of fringe
for minimum thickness
n = 0
2μt = λ / 2
t = λ / 4μ
= 670 / 1.75 x 4
= 95.71 nm .
Actually, when the refrigeration liquid is vaporized, the cooling effect is produced
Answer:

Explanation:
Since <em>light is so fast</em> we can assume no time passes between the lightning strikes and we observe it. We want to know then how far away did the strike occur for the sound to take 16s to reach our ears. Since the definition of velocity tells us that
, we can write 
A net torque of magnitude is 600
Answer:
-2
Explanation:
Since its a compound, it's charge is 0.
So, there are 2 Fe and 3 Oxygen,
let x = oxidation number of oxygen
2(+3) + 3x =0
x =-2
Side note : even if the oxidation number is positive, make sure to put the positive sign like how you would in numbers