Question

Two equal balls having equal positive charge q coulombs are suspended by two insulating strings of equal length. What would be the effect on the force when a plastic sheet is inserted between the two?

Answer 1

In physics, a force is any influence that, when unopposed, causes an object to change its velocity. A force can cause a mass item to change its velocity (which includes starting to move from a standstill), i.e. accelerate. Intuitively, force may be characterised as a push or a pull. A force is a vector quantity since it has both magnitude and direction. The SI unit of Newton is used to measure it (N). The letter F is used to signify force.

Complete step by step solution:
Coulomb's law is a physics experiment that measures the force between two stationary, electrically charged particles. Electrostatic force, also known as Coulomb force, is the electric force between charged substances at rest. Coulomb's law was crucial to the development of electromagnetic theory, maybe even its inception, because it allowed us to talk about the quantity of electric charge in a meaningful way. The electrostatic force of attraction or repulsion between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of their distance, according to the law.
$F = k\dfrac{{{q_1}{q_2}}}{{{r^2}}}$
Although it is sometimes written as the following product of the vacuum permittivity constant, the Coulomb constant is utilised in many electric equations: ${k_{\text{e}}} = \dfrac{1}{{4\pi {\varepsilon _0}}}$
Now according to the given question
Force will decrease.
This is due to the reason that the Force between two charges each ‘q’ in vacuum is
${F_o}{\text{ }} = {\text{ }}\dfrac{1}{{4\pi {\varepsilon _0}}}.\dfrac{{{\text{ }}{q^2}}}{{{r^2}}}$
On inserting a plastic sheet (a dielectric K > 1)
Then $F{\text{ }} = {\text{ }}\dfrac{1}{{4\pi {\varepsilon _0}}}.\dfrac{{{\text{ }}{q^2}}}{{{r^2}}}$
i.e Force $F{\text{ }} = {\text{ }}\dfrac{{{F_0}}}{K}$
Hence, The force between charged balls will decrease.

Note:
The absolute permittivity, often known as permittivity and symbolised by the Greek letter, is a measure of a dielectric's electric polarizability in electromagnetism. A material with a high permittivity polarises more in response to an applied electric field than one with a low permittivity, allowing it to store more energy. The permittivity of a capacitor is essential in electrostatics because it determines its capacitance.