Answer:
It's letter B that's all I know
Explanation:
It is given that,
Wavelength of a beam of light in vacuum, 
(a) Let v is the speed of light in a liquid whose index of refraction at this wavelength is 1.56.
We know that,
Refractive index,

(b) The wavelength of light in material,

Let
is the wavelength of these waves in the liquid. So,

Hence, this is the required solution.
Answer:
d = 4180.3m
wavelengt of sound is 0.251m
Explanation:
Given that
frequency of the sound is 5920 Hz
v=1485m/s
t=5.63s
let d represent distance from the vessel to the ocean bottom.
an echo travels a distance equivalent to 2d, that is to and fro after it reflects from the obstacle.


wavelengt of sound is
= v/f
= (1485)/(5920)
= 0.251 m
The correct answer to the question is: 78.4 N.
CALCULATION:
As per the question, the mass of the object is given as m = 8 Kg.
We are asked to calculate the force of 8 Kg object pushing up from the table.
The force pushing up from the table is nothing else than the normal reaction.
The normal reaction of the object is equal to the weight of the object as the object is simply resting on the table.
Hence, normal reaction = Weight
= mg
= 8 × 9.8 N.
= 78.4 N.
Here, g is known as acceleration due to gravity.
Hence, the force of the object pushing up from the table is 78.4 N.