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KCET · Physics · Electrostatics

A potential at a point A is -3 V and that at another point B is 5 V . What is the work done in carrying a charge of 5 m C from B to A ?

  1. A -0.04 J
  2. B -0.4 J
  3. C -4 J
  4. D -40 J
Verified Solution

Answer & Solution

Correct Answer

(A) -0.04 J

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \text { Wext }=q \Delta V \\ & =q\left(V_f-V_i\right) \\ & =5 \times 10^{-3}\left(V_A-V_B\right) \\ & =5 \times 10^{-3}(-3-5) \\ & =-8 \times 5 \times 10^{-3} \mathrm{~J} \\ & =-40 \times 10^{-3} \mathrm{~J} \\ & =-0.04 \mathrm{~J}\end{aligned}\)