Since the time of the Greeks some 2600 years ago, Thales of Miletus has noticed the phenomenon of …show more content…
To make this formula exactly, it means changing a comparable sign (α) with a = sign, then a constant is required, say k where:
F = k QA QB / r AB (1)
The value of k is known as the Coulomb constant. But what is the magnitude of this constant? Before Coulomb, Cavendish had actually used the same principle when he calculated the constant G on the universal gravitational force. But he did not publish it and was too late to recognize people than Coulomb who published his works through the Mémoirs de l'Académie Royale between 1775 and …show more content…
It consists of two spherical balls each m and radius r connected to a light rod called "dumbell". This dumbbel can spin back and forth because it rejected the electrostatic force of two other balls of mass M.
This repulsive force is proportional to torque with τ = F. (d / 2), so that if the torque can be measured the force can be measured and if the charge and the known distance k value can be obtained from the equation (1): k = F. r AB / Q A Q B
To measure the torque, a Hooke relationship is used in which: τ = c. θ c This is the elastic modulus of the wire that can be measured from with calculate the dumbell oscillation device with:
T = 2 π√I / c c = 4π2I / T2
I is the moment of inertia, to dumbell the value I = 2m (d2 + 2r2 / 5). So if d, r, m and T can be calculated then in principle we can get the value k. The k value of the measurement is bout 9x109 Nm2 / C2, this value is for the air or vacuum