Electric Charges and Fields — Physics STD 12 Science — Question
Gujarat BoardEnglish MediumSTD 12 SciencePhysicsElectric Charges and Fields2 Marks
Question
Write down the Coulomb's law and explain its scalar form.
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Answer
→ Coulomb's law : "The electric force (Coulomb force) between two stationary point charge is proporational to the product of the values of the charge and inversely proportional to the square of the distance between them the direction of this force is along the direction of the line joining the two charges." → Two point charges $q_1, q_2$ are separated by a distance $r$ in vacuum, the magnitude of the force $( F )$ between them is given by $F =k \frac{q_1 q_2}{r^2}$ Where $k$ is constant $k=9 \times 10^9 Nm ^2 / C ^2$ → To simplify many formulas related to electricity $\frac{1}{4 \pi \varepsilon_0}$ is taken in place of $k$ in SI system. From equation (1) $F =\frac{1}{4 \pi \varepsilon_0} \cdot \frac{q_1 q_2}{r^2}$ Where, $\varepsilon_0$ is called the permittivity of free space. $\begin{array}{l} \varepsilon_0=8.85 \times 10^{-12} C ^2 / Nm ^2 \\ \quad\left( M ^{-1} L^{-3} T^2 Q ^2 OR M ^{-1} L^{-3} T^4 A^2\right) \end{array}$ → Because the coulomb's force acts between two charges only, it is also called two body force. → For coulomb's law F $\propto \frac{1}{r^2}$ that's why it is also called inverse square law.
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