Sample 1Medium
Two point charges are fixed on the x-axis: +4q at x = 0 and +q at x = 3 m. A small positive test charge can be placed anywhere on the line between them. At what position does the test charge experience zero net force?
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The answer is C.
The two repulsions balance where 4q/x² = q/(3 − x)², so 2(3 − x) = x and x = 2 m, nearer the smaller charge.
- A.
At x = 1 m the force from +4q is greater.
- B.
The midpoint balances only equal charges.
- D.
At x = 2.5 m the force from +q is greater.
NCERT: Class 12 Physics, Chapter 1