PhysicsLAB: 2006 B3

AP Free Response Question
2006 B3

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Two point charges, q₁ and q₂ , are placed 0.30 m apart on the x-axis, as shown in the figure above. Charge q₁ has a value of —3.0 x 10^-9 C. The net electric field at point P is zero.

	(a) What is the sign of charge q₂: positive or negative? Justify your answer.

	(b) Calculate the magnitude of charge q₂.

	(c) Calculate the magnitude of the electric force on q₂ and indicate its direction.

	(d) Determine the x-coordinate of the point on the line between the two charges at which the electric potential is zero.

	(e) How much work must be done by an external force to bring an electron from infinity to the point at which the electric potential is zero? Explain your reasoning.

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