Answer:
For destructive interference phase difference is
where n∈ Whole numbers
Explanation:
For sinusoidal wave the interference affects the resultant intensity of the waves.
In the given example we have two waves interfering at a phase difference of 
would lead to a constructive interference giving maximum amplitude at at the RMS value of the amplitude in resultant.
Also the effect is same as having a phase difference of 
because after each 2π the waves repeat itself.
<em>In case of destructive interference the waves will be out of phase i.e. the amplitude vectors will be equally opposite in the direction at the same place on the same time as shown in figure.</em>
They have a phase difference of 
or which is same as 
Generalizing to:
a phase difference of where n∈ {W}
{W}= set of whole numbers.
If you go to high you’ll run out of oxygen and possibly be blown off due to high winds.
Answer
D.Diffraction
Explanation
Diffraction is a property that is experienced by waves when they come across a barrier when they are in motion.
The ways tends to curve behind the barrier. This is called diffraction of waves.
Now, sound is a wave and it also experience diffraction. . So the brother will be able to hear the sound due to diffraction
The reason why icebergs float in the ocean has to do with temperature. Icebergs are colder than the ocean water and therefore the cold water is less dense than the warm water and this causes the Iceberg to float.
Answer:
The hypothesis may or may not be true and needs to be tested. It might be the answer to the problem. Hence, it must be tested thoroughly. When these predictions are tested again and again in independent scientific experiments and gets verified, the hypothesis is converted into a scientific theory.
