Answer:
Explanation:
Our lunar companion rotates while it orbits Earth. It's just that the amount of time it takes the moon to complete a revolution on its axis is the same it takes to circle our planet — about 27 days. As a result, the same lunar hemisphere always faces Earth.
Answer:

Explanation:
From the question we are told that:
Far point is 
Near point is 
Therefore
Focal Length

Generally the equation for the Lens is mathematically given by



Answer:
because the mass of the copper is higher than the mass of the gold.
Explanation:
Photon is a quantum of light or a single packet/particle of light at a given wavelength.
Answer: Option B
<u>Explanation:
</u>
It is known that light has dual nature of wave as well as particles. Light waves can behave in wave nature as well as in particle nature depending upon the situation. So the light waves are assumed in different views to easily understand the nature of light waves.
There are several models proposed to simplify the nature of light. Among the several assumptions, one of the most prominent observations are that light waves or quantum of light are termed as photons which are made up of single packet/particles of light in a given wavelength.