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An electric heating coil rated at 1Kw is used to heat 2kg...

An electric heating coil rated at 1Kw is used to heat 2kg of water for 2 minutes. The initial water temperature is 30oC. Taking the specific heat of the water as 4,000Jkg 1 and neglecting that of the container, the final water temperature is

A.

15.0oC

B.

45.0oC

C.

52.5oC

D.

60.0oC

Correct answer is B

  Time = 2mins = 2 × 60 = 120secs

  Energy = power × time

  1000 × 120 = 120,000J

  Energy = mc(θ2 – θ1)

  120,000 = 2 × 4000(θ2 – θ1)

  θ2 = 30 + 15 = 45 o C