Question:medium

The distance between two charges \( q_1 = +2 \, \mu C \) and \( q_2 = +8 \, \mu C \) is 15 cm. Calculate the distance from the charge \( q_1 \) to the points on the line segment joining the two charges where the electric field is zero.

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To find the point where the electric field is zero between two charges, set up an equation equating the electric fields due to both charges and solve for the distance.
Updated On: Apr 18, 2026
  • 1 cm
  • 2 cm
  • 3 cm
  • 4 cm
  • 5 cm
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Solution and Explanation

Step 1: Understanding the Concept
The "neutral point" is the location where the electric fields produced by the two charges are equal in magnitude but opposite in direction, resulting in a net field of zero.
Step 2: Key Formula or Approach
Let the distance from \(q_1\) be \(x\). The distance from \(q_2\) will be \((15 - x)\). At the neutral point: \[ E_1 = E_2 \implies \frac{k q_1}{x^2} = \frac{k q_2}{(15-x)^2} \]
Step 3: Detailed Calculation
1. Substitute the values: \[ \frac{2}{x^2} = \frac{8}{(15-x)^2} \] 2. Simplify the ratio: \[ \frac{1}{x^2} = \frac{4}{(15-x)^2} \] 3. Take the square root of both sides: \[ \frac{1}{x} = \frac{2}{15-x} \] 4. Cross-multiply and solve for \(x\): \[ 15 - x = 2x \implies 15 = 3x \implies x = 5 \text{ cm} \]
Step 4: Final Answer
The distance from \(q_1\) is 5 cm.
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