91Ó°ÊÓ

In Fig. 22-66, particle 1 (of charge $\mathbf{+}\mathbf{2}\mathbf{.00}\mathbf{\text{pC}}$), particle 2 (of charge$\mathbf{−}\mathbf{2}\mathbf{.00}\mathbf{\text{pC}}$), and particle 3 (of charge$\mathbf{+}\mathbf{5}\mathbf{.00}\mathbf{\text{pC}}$) form an equilateral triangle of edge length $\mathit{a}\mathbf{}\mathbf{=}\mathbf{9}\mathbf{.50}\mathbf{\text{cm}}$.

(a) Relative to the positive direction of the x-axisdetermines the direction of the force $\stackrel{\mathbf{→}}{{\mathbf{F}}_{\mathbf{3}}}$on particle 3 due to the other particles by sketchingelectric field lines of the other particles.

(b) Calculate the magnitude of$\stackrel{\mathbf{→}}{{\mathbf{F}}_{\mathbf{3}}}$

In Fig. 22-69, particle 1 of charge${\mathit{q}}_{\mathbf{1}}\mathbf{=}\mathbf{1}\mathbf{.00}\mathbf{\text{pC}}$and particle 2 of charge${\mathit{q}}_{\mathbf{2}}\mathbf{=}\mathbf{2}\mathbf{.00}\mathbf{\text{pC}}$are fixed at a distance$\mathit{d}\mathbf{}\mathbf{=}\mathbf{5}\mathbf{.00}\mathbf{}\mathit{c}\mathit{m}$apart. In unit-vector notation, what is the net electric field at points

(a) A,

(b) B, and

(c) C?

(d) Sketch the electric field lines.

In Fig. 22-36, the four particles are fixed in place and have charges,${\mathbf{q}}_{\mathbf{1}}\mathbf{=}{\mathbf{q}}_{\mathbf{2}}\mathbf{=}\mathbf{+}\mathbf{5}\mathbf{e}\mathbf{}\mathbf{,}{\mathbf{q}}_{\mathbf{3}}\mathbf{}\mathbf{=}\mathbf{+}\mathbf{3}\mathbf{e}\mathbf{}\mathbf{and}\mathbf{}{\mathbf{q}}_{\mathbf{4}}\mathbf{=}\mathbf{-}\mathbf{12}\mathbf{e}$. Distance, d = 5.0 mm. What is the magnitude of the net electric field at point Pdue to the particles?

Figure 22-37 shows two charged particles on an x-axis: $\mathbf{-}\mathbf{q}\mathbf{=}\mathbf{-}\mathbf{3}\mathbf{.}\mathbf{20}\mathbf{×}{\mathbf{10}}^{\mathbf{-}\mathbf{19}}\mathbf{C}$at $\mathbf{x}\mathbf{=}\mathbf{-}\mathbf{3}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{m}$$\mathbf{q}\mathbf{=}\mathbf{3}\mathbf{.}\mathbf{20}\mathbf{×}{\mathbf{10}}^{\mathbf{-}\mathbf{19}}$and at $\mathit{x}\mathbf{=}\mathbf{+}\mathbf{3}\mathbf{.}\mathbf{00}\mathbf{}\mathbf{m}$. What are the (a) magnitude and (b) direction (relative to the positive direction of the x-axis) of the net electric field produced at point Pat $\mathbf{y}\mathbf{=}\mathbf{4}\mathbf{.}\mathbf{00}\mathbf{m}$?

Figure 22-28 shows two disks and a flat ring, each with the same uniform charge Q. Rank the objects according to the magnitude of the electric field they create at points P(which are at the same vertical heights), greatest first.