Answer:
The depth of focus achievable with those lenses is small.
Explanation:
A larger aperture makes it much harder to focus on more than one object. When using a telephoto lens (the ones the question is referring to), the depth of focus is very small. For example, using a telephoto lens to take a photo of a runner might get the runner in focus, but certainly not the track, or the audience behind them. If you look at photos, especially older photos, of Olympians in almost any sport you can see this.
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The electric field strength is inversely related to the square of the distance.so the strength of the electric field is given by
Here, 
is constant depend upon medium and its value is 
and q is charge and r is the distance.
Given 
and we know the charge of proton, 
.
Therefore,
"The <span>ground is positively charged and the clouds are negatively charged " is the statement among the statements given in the question that </span><span>best explains the movement of electric current from the clouds to the ground during a lightning storm. The correct option among all the options that are given in the question is the third option or option "C". </span>
