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Point charges of 4.75 µC and −1.50 µC are placed 0.350 m apart. (Assume the negative charge is located to the right of the positive charge.
Question
Point charges of 4.75 µC and −1.50 µC are placed 0.350 m apart. (Assume the negative charge is located to the right of the positive charge. Include the sign of the value in your answers.)
(a) Where can a third charge be placed so that the net force on it is zero?
_______ m to the right of the −1.50 µC charge
(b) What if both charges are positive?
_______ m to the right of the 1.50 µC charge
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2021-09-04T22:48:05+00:00
2021-09-04T22:48:05+00:00 1 Answers
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Answer:
Explanation:
Let the position of balance point be x distance from 1.5 µC on the right side . Balance point can not be on the left side or between the charges because in that case electric field by both the charges will be in the same direction .
For equilibrium of field
k x 4.75 µC / ( .35 +x )² – k x 1.5 µC / x ² = 0
4.75 / ( .35 +x )² = 1.5 / x²
( .35 +x )² / x² = 4.75 / 1.5
( .35 +x )² / x² = 3.167
( .35 +x ) / x = 1.78
.35 + x = 1.78 x
.78 x = .35
x = .45 m ( + ve ) to the right of 1.50 µC
b ) When both the charges are positive , balance point will lie in between them because , electric field will be in opposite direction .
For equilibrium of field
k x 4.75 µC / ( .35 – x )² = k x 1.5 µC / x ²
4.75 / ( .35 -x )² = 1.5 / x²
( .35 -x )² / x² = 4.75 / 1.5
( .35 -x )² / x² = 3.167
( .35 -x ) / x = 1.78
.35 -x = 1.78 x
2.78 x = .35
x = .126 m ( – ve ) to the right of 1.50 µC