An electric heating coil rated at 1Kw is used to heat 2kg of water for 2 minutes. The initial water temperature is 30\(^o\)C. Taking the specific heat of the water as 4,000Jkg \(^{-1}\) and neglecting that of the container, the final water temperature is
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Correct Answer: Option B
Explanation:
Power = 1kw=100W
 Time = 2mins = 2 × 60 = 120secs
 Energy = power × time
 1000 × 120 = 120,000J
 Energy = mc(θ\(_2\) – θ\(_1\))
 120,000 = 2 × 4000(θ\(_2\) – θ\(_1\))
 θ2 = 30 + 15 = 45 \(^o\) C
Power = 1kw=100W
 Time = 2mins = 2 × 60 = 120secs
 Energy = power × time
 1000 × 120 = 120,000J
 Energy = mc(θ\(_2\) – θ\(_1\))
 120,000 = 2 × 4000(θ\(_2\) – θ\(_1\))
 θ2 = 30 + 15 = 45 \(^o\) C