Answer :
F"=4F/9 or F"=4F ÷9 is the magnitude for the force acting on the 4q charge.
Coulomb's law states that the magnitude of the forces between Q and 4Q is,
F'=КQ×4Q÷d²
= 4F ---------------------------(1)
Now, if the distance is made 3 times greater than before, or in three dimensions,
F''=КQ×4Q÷ (3d)²
Or F''= 4КQ² ÷ 9d²
or, F''= 4÷9 × ₍КQ²÷ d²₎
or, F''= 4F/9
Coulomb's law: a rule indicating that opposing charges attract and similar charges repel, with a force proportional to the product of the charges and inversely proportional to the square of the space between them.
Dimensions: an area that may be measured for its length, width, depth, or height.
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