Ch 22: Electric Force & Field; Gauss' LawWorksheetSee all chapters
All Chapters
Ch 01: Units & Vectors
Ch 02: 1D Motion (Kinematics)
Ch 03: 2D Motion (Projectile Motion)
Ch 04: Intro to Forces (Dynamics)
Ch 05: Friction, Inclines, Systems
Ch 06: Centripetal Forces & Gravitation
Ch 07: Work & Energy
Ch 08: Conservation of Energy
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Ch 10: Rotational Kinematics
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Ch 18: Heat and Temperature
Ch 19: Kinetic Theory of Ideal Gasses
Ch 20: The First Law of Thermodynamics
Ch 21: The Second Law of Thermodynamics
Ch 22: Electric Force & Field; Gauss' Law
Ch 23: Electric Potential
Ch 24: Capacitors & Dielectrics
Ch 25: Resistors & DC Circuits
Ch 26: Magnetic Fields and Forces
Ch 27: Sources of Magnetic Field
Ch 28: Induction and Inductance
Ch 29: Alternating Current
Ch 30: Electromagnetic Waves
Ch 31: Geometric Optics
Ch 32: Wave Optics
Ch 34: Special Relativity
Ch 35: Particle-Wave Duality
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Ch 38: Quantum Mechanics

Solution: An equilateral triangle  ABC. A positive point charge +q is located at each of the three vertices A, B, and C. Each side of the triangle is of length  a. A point charge Q (that may be positive or nega

Problem

An equilateral triangle  ABC. A positive point charge +q is located at each of the three vertices A, B, and C. Each side of the triangle is of length  a. A point charge Q (that may be positive or negative) is placed at the mid-point between  B and C. Is it possible to choose the value of Q (that is non-zero) such that the force on Q is zero?

A) Yes, because the forces on Q are vectors and three vectors can add to zero.

B) No, because the forces on Q are vectors and three vectors can never add to zero.

C) Yes, because the electric force at the mid-point between  B and C is zero whether a charge is placed there or not.

D) No, because the forces on Q due to the charges at  B and C point in the same direction.

E) No, because a fourth charge would be needed to cancel the force on  Q due to the charge at  A.