Question

Two charges q₁ and q₂ are placed 30 cm apart, as shown in the figure. A third charge q₃ is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is $\frac{q_{3}}{4\pi \in_{0}}$k, where k is –

• A. 8q₁
• B. 6q₁
• C. 8q₂
• D. 6q₂

Answer 1

Answer: (C)

8q₂

Answer 2

U₁ = $\frac{kq_{1}q_{3}}{0.4} + \frac{kq_{1}q_{2}}{0.3} + \frac{kq_{2}q_{3}}{0.5}$

$U_{2} = \frac{kq_{1}q_{2}}{0.3} + \frac{kq_{2}q_{3}}{0.1} + \frac{kq_{1}q_{3}}{0.4}$

\ DU = 8 kq₂ q₃ = 8q₂ $\left( \frac{q_{3}}{4\pi\varepsilon_{0}} \right)$ Ž k = 8q₂