Answer:
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Answer
given,
wavelength (λ)= 500 n m
thickness of film= 10⁻⁴ cm
refractive index = μ = 1.375
distance traveled is double which is equal to 2 x 10⁻⁴ cm
a) Number of wave


N = 2.91
N = 3
b) phase difference is equal to
Reflection from the first surface has a 180° (½λ) phase change.
There is no phase change for the 2nd surface reflection and there is no phase difference for the 2nd wave having traveled an exact whole number of waves.
net phase difference = 
= 270°
Celina should perform the following method to get pure water:
Boil the water in a pan, as the water boils it changes into gas (water vapours) these vapours should be cooled down through the process of condensation which changes gas into liquid form, Through this process germs would be killed due to high temperature and the salt will remain in the pan as salt has higher boiling point than water,
Answer:
Potential gravitational energy is the energy that the body has due to the Earth's gravitational attraction. In this way, the potential gravitational energy depends on the position of the body in relation to a reference level.
Explanation: