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JEE Main 20211 SeptemberEvening Shift
Exam
JEE Main
Year
2021
Date
1 September
Shift
Evening Shift
Subject
Physics
Chapter
Thermal Properties of Matter

JEE Main 2021 · 1 September · Evening Shift · Physics · Thermal Properties of Matter

Due to cold weather, a 1m water pipe of cross-sectional area 1 cm ^...

Due to cold weather, a 1m1m water pipe of cross-sectional area 1cm21{cm}^{2} is filled with ice at −10°C.- 10 ° C . Resistive heating is used to melt the ice. Current of 0.5A0 . 5A is passed through 4kΩ4kΩ resistance. Assuming that all the heat produced is used for melting, what is the minimum time required?

(Given latent heat of fusion for water/ice=3.33×105Jkg−1,= 3 . 33 \times {10}^{5}J{kg}^{- 1}, specific heat of ice =2×103Jkg−1°C−1= 2 \times {10}^{3}J{kg}^{- 1} ° {C}^{- 1} and density of ice =103kgm−3)= {10}^{3}kg{m}^{- 3} )

Options

  1. A3.53s3 . 53s
  2. B0.353s0 . 353s
  3. C35.3s35 . 3s
  4. D70.6s70 . 6s

Correct answer

C. 35.3s35 . 3s

Step-by-step solution

The mass of ice, m=ρAL=103×10−4×1=10−1kgm = ρAL = {10}^{3} \times {10}^{- 4} \times 1 = {10}^{- 1}kg,

Energy required to melt the ice, =mS\DeltaT+mL= mS\DeltaT + mL,

⇒i2Rt=mS\DeltaT+mL⇒ {i}^{2}Rt = mS\DeltaT + mL
⇒(1)2×103×t=[(103×1×10−4)×2000×10]+[(103×1×10−4)×330×103]⇒(1)2×103×t=3.53×104⇒t=35.3s⇒ ( 1{)}^{2} \times {10}^{3} \times t = \left[\left({10}^{3} \times 1 \times {10}^{- 4}\right) \times 2000 \times 10\right] + \left[\left({10}^{3} \times 1 \times {10}^{- 4}\right) \times 330 \times {10}^{3}\right] ⇒ ( 1{)}^{2} \times {10}^{3} \times t = 3 . 53 \times {10}^{4} ⇒ t = 35 . 3s

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