Figure a shows three particles on an x axis. Particle 1 (with a charge of + 5.0C) and particle 2 (with a charge of +

Figure a shows three particles on an x axis. Particle 1 (with a charge of + 5.0μC) and particle 2 (with a charge of + 3.0μC) are fixed in place with separation d = 4.0 cm. Particle 3 can be moved along the x axis to the right of particle 2. Figure b gives the electric potential energy U of the three-particle system as a function of the x coordinate of particle 3. The scale of the vertical axis is set by Us = 5.0J. What is the charge of particle 3?

U, x (cm) 20 10 -U, (a) (b)