The answer to the question is sound
Answer:
(a) 
(b) 
(c)
(d)
Solution:
As per the question:
Refractive index of medium 1, 
Angle of refraction for medium 1, 
Angle of refraction for medium 2, 
Now,
(a) The expression for the refractive index of medium 2 is given by using Snell's law:

where
= Refractive Index of medium 2
Now,

(b) The refractive index of medium 2 can be calculated by using the expression in part (a) as:


(c) To calculate the velocity of light in medium 1:
We know that:
Thus for medium 1
(d) To calculate the velocity of light in medium 2:
For medium 2:
Answer:
A Mold
Explanation:
A mold forms when hard parts of an organism are buried in sediment; the hard parts completely dissolve over time, leaving behind a hollow area. A cast forms as a result of a mold when minerals and sediment fill in the impression.
The moon, because the acceleration due to gravity is less.
Answer:
r₂=0.1 m
Explanation:
Given that
r₁= 10 m , β₁ = 20 dB
At r₂ ,β₂= 60 dB
As we know that intensity level of sound given as



10² x 10⁻¹² = I₁
I₁=10⁻¹⁰ W/m²


10⁶ x 10⁻¹² = I₂
I₂ = 10⁻⁶ W/m²
I₁=10⁻¹⁰ W/m²
P = I A
P=Power ,I =Intensity ,A=Area


r₂=0.1 m