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JAMB Physics 2007 Objective — Question 40

Question 40 of 50 from the Joint Admissions and Matriculation Board (JAMB) Physics 2007 Objective paper, with the correct answer and a full explanation.

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2kg of water is heated with a heating coil which draws 3.5A on a 200V mains for 2 minutes. What is the increase in temperature of the water? [Specific heat capacity of water = 4200 Jkg-1K-1]

  • A. 25 C
  • B. 15 C
  • C. 10 CCorrect
  • D. 30 C

Explanation

Electrical energy = Heat energy: IVt = mc(delta theta). Delta theta = (3.5x200x2x60)/(2x4200) = 10 C.

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