# Electric Charge

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HW 1 solutions Point Charge in One Dimension A point charge q1 = -3.5 μC is located at the origin of a co-ordinate system. Another point charge q2 = 5.1 μC is located along the x-axis at a distance x2 = 9.3 cm from q1. 1) What is F12,x, the value of the x-component of the force that q1 exerts on q2? -18.57 N For all of these problems we want to make use of the standard electric force equation: ̂ So for this problem with K=9*109 Nm2/C2, Q1=-3.5μC, Q2=5.1 μC, and r=9.3 cm we get F=-18.57 N. It’s important to realize that getting a negative force value means the charges attract. The direction of that attraction is determined by which charge we’re looking at. 2) Charge q2 is now displaced a distance y2 = 2.7 cm in the positive…show more content…
This gives us Ex=kλ/r or in our case Ex=kλ/a. 3) What is Ey, the value of the y-component of the electric field at the origin (x,y) = (0,0) ? 1.52E6 N/C Since the curve is symmetric and spread along a 45° angle there will be no difference between the X and Y E-fields. 5) What is the magnitude of the electric field at the origin produced by a semi-circular arc of charge = -4.6 μC, twice the charge of the quarter-circle arc? 3.05E6 N/C All that doubling the charge does is make sure we have the same charge density as before, twice the charge but twice the length. Since we already know Ey for the quarter arc, the Ey for the semicircle will be twice that. The Ex for the two parts of the semicircle cancel each other