STANDARDPhysics-Thermodynamics
STANDARD Physics First Law of Thermodynamics MCQ Question
Type: MCQ-numerical-Medium-Class 11
An electric heater supplies heat to a system at a rate of 120 W. If system performs work at a rate of 80 J s⁻¹, the rate of increase in internal energy is
A
30 J s⁻¹
B
40 J s⁻¹
C
50 J s⁻¹
D
60 J s⁻¹
Correct Answer
Option B
Detailed Explanation
According to first Law of thermodynamics ΔQ = ΔU + ΔW. Here, ΔQ/Δt = 120 W, ΔW/Δt = 80 J s⁻¹. Therefore, ΔU/Δt = 120 - 80 = 40 J s⁻¹.
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