A Charge Q = -610 NC Is Uniformly Distributed on a Ring

question 9

Multiple Choice

A charge Q = -610 nC is uniformly distributed on a ring of 2.4-m radius. A point charge q = +480 nC is fixed at the center of the ring, as shown in the figure. An electron is projected from infinity toward the ring along the axis of the ring. This electron comes to a momentary halt at a point on the axis that is 5.0 m from the center of the ring. What is the initial speed of the electron at infinity? (e = 1.60 × 10^-19 C, k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C², m_el = 9.11 × 10^-31 kg )

• A) 6.6 × 10⁶ m/s
• B) 4.5 × 10⁶ m/s
• C) 3.4 × 10⁶ m/s
• D) 2.2 × 10⁶ m/s
• E) 1.1 × 10⁶ m/s

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