Question 40
Quantity of Heat2 kg of water is heated with a heating coil which draws 3.5 A from a 200 V mains for 2 minutes. What is the increase in temperature of the water? [Specific heat capacity of water = 4200 Jkg−1 K−1]
- A.25°C
- B.15°C
- C.10°C
- D.30°C
Show the answer and explanation
Answer: C (10°C)
Explanation
Heat supplied = IVt = 3.5 × 200 × 120 = 84 000 J. Δθ = 84 000 ÷ (2 × 4200) = 10°C.