7.00 μC 0.500 m 60.0° 60.0°, 2.00 μC -4.00 μC Figure P15.13

Review Conceptual Example 11 before attempting to work this problem. Four charges with equal magnitudes of 9.24 x 10-12 Care placed at the corners of a rectangle. The lengths of the sides of the rectangles are 3.23 cm and 6.21 cm. Find the magnitude of the electric field at the center of the rectangle in Figures a and b. (a) Number (b) Number i i 2, E13 E24 E24 44 3 +9 +9 +9 4 +4 Units Units (b) +9

Four charges of the same magnitude of q = 1.0 nC are placed in a corners of a square with the side of a = 10 cm. See the figure for the charge signs. Find the electric field (magnitude and direction) in the center of the square. +q a +q a -9 a -9 Select one: O 30750 N/C, leftward O 5090 N/C rightward O 30750 N/C, rightward O 50900 N/C, leftward O5090 N/C, leftward O 50900 N/C, rightward

A 148 mg plastic bead has a radius of 344 μm and is charged by the addition of 1.38×1010 excess electrons. You may assume that the excess electrons are spread uniformly throughout the bead. What electric field strength will cause the bead to hang suspended in the air?

An infinite line of positive charge lies along the y axis, with charge density A = 1.10 µC/m. A dipole is placed with its center along the x axis at x = 21.0 cm. The dipole consists of two charges ±10.0 µuC separated by 2.00 cm. The axis of the dipole makes an angle of 25.0° with the x axis, and the positive charge is farther from the line of charge than the negative charge. Find the net force exerted on the dipole.

P6E4

The drawing shows two situations in which charges are placed on the x and y axes. They are all located at the same distance of 5.00 cm from the origin O. For each of the situations in the drawing, determine the magnitude of the net electric field at the origin. -l.0 μC +1.0 uC +2.0 uC -3.0 µC +4.0 µC -1.0 uC o! +6.0 uC (b) (a)

Two point charges are lying on the y- axis as in the figure: q₁ = -4.10 μC and 92 = +4.10 µC. They are equidistant from the point P, which lies on the x- axis. (a) What is the magnitude of net electric field at P? (b) A small object of charge qo = 7.30 µC and mass m = 1.24 g is placed at P. When it is released, what is the magnitude of its acceleration? 91 92 + (a) Number (b) Number 0.880m 31.5 31.5° 0.880 m +x Units Units !!

Three point charges are located on a circular arc as Q2 shown in Figure P23.31. (a) What is the total electric field at P, the center of the arc? (b) Find the elec- tric force that would be exerted on a –5.00-nC point charge placed at P. +3.00 nC 4.00 cm -2.00 nC 30.0° P 30.0° 4.00 cm +3.00 nC Figure P23.31

The cockroach Periplaneta americana can detect a static electric field of magnitude 9.00 kN/C using their long antennae. If the excess static charge on a cockroach is modeled as point charges located at the end of each antenna, what magnitude of charge q would each antenna possess in order for each antennae to experience a force of magnitude 4.50 µN from the external electric field? Calculate q in units of nanocoulombs (nC). q = nC