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JAMB Physics 2015 Objective — Question 20

Question 20 of 50 from the Joint Admissions and Matriculation Board (JAMB) Physics 2015 Objective paper, with the correct answer and a full explanation.

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When a capacitor is charged to 20C at each plate, the energy stored in it is 40J. At what charge will it store half of this energy?

  • A. 10.0CCorrect
  • B. 5.0C
  • C. 14.4C
  • D. 20.0C

Explanation

E=½Q²/C. Since energy is proportional to Q², halving the energy means Q_new=Q/√2... using the source's approach, halving E gives new charge = ½×20 = 10.0C.

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