A point charge of 10 μC is placed at the origin. At what location on the X-axis should a point charge of 40 μC be placed so that the net electric field is zero at x = 2 cm on the X-axis ?
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A point charge of 10 μC is placed at the origin. At what location on the X-axis should a point charge of 40 μC be placed so that the net electric field is zero at x = 2 cm on the X-axis ?

G1 Physics · Accepted Answer

At x = 2 cm, the fields must be equal and opposite: k(10)/(2²) = k(40)/(x₀ - 2)². Hence (x₀ - 2)² = 16, and for the second charge to lie to the right so that its field is opposite, x₀ - 2 = 4. Therefore x₀ = 6 cm.