What is the nature of electrostatic force between two point electric charges q₁ and q₂ if (a) q₁ + q₂ > 0 (b) q₁ × q₂ < 0 ?
✅ Answer & Solution
<b>Concept:</b> The nature of electrostatic force depends on the <b>product</b> of charges, not on their sum.<br><br>
<b>Rules:</b><br>
• If q<sub>1</sub> × q<sub>2</sub> > 0 → charges have same sign → <b>Repulsive force</b><br>
• If q<sub>1</sub> × q<sub>2</sub> < 0 → charges have opposite signs → <b>Attractive force</b><br><br>
<b>Case (a): q<sub>1</sub> + q<sub>2</sub> > 0</b><br><br>
A positive sum does <b>not</b> determine whether the force is attractive or repulsive.<br><br>
<b>Examples:</b><br>
• q<sub>1</sub> is +5, q<sub>2</sub> is +3 → Product +15 → <b>Repulsive</b><br>
• q<sub>1</sub> is +5, q<sub>2</sub> is −3 → Sum +2 (>0), Product −15 → <b>Attractive</b><br><br>
<b>Conclusion (a):</b> Force may be attractive or repulsive. Hence, it <b>cannot be determined</b> from the sum alone.<br><br>
<b>Case (b): q<sub>1</sub> × q<sub>2</sub> < 0</b><br><br>
A negative product means charges are of <b>opposite signs</b>.<br><br>
<b>Conclusion (b):</b> The electrostatic force between them is <b>Attractive</b>.
✅ Verified by Super Admin
