According to Coulomb's Law , The size of the force varies inversely as the square of the distance between the two charges. So ,if the distance between the two charges is doubled, the electrostatic force will become weak by one fourth of the original force.
Thew energy stored in a capacitor of capacitance 
and voltage between the plates 
is
.
Substituting numerical value
Your answer is electricity, light and magnetism. They can be determined usinf elecromagnetic radioation.
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Even the energy can't be detected by our eyes, there are a lot of measurement instruments that can measure infrared (IR), gamma rays, radio or X-rays or ultraviolet (UV)</span>
It is strong enough to penetrate through flesh but not bone so we can see if there are fractures or breaks in our skeleton
