A 120 V a.c. voltage source is connected across a pure 25.0 mH inductor. Find the current through th

JAMB Physics 2023 167 views
Source: JAMB · 2023

A 120 V a.c. voltage source is connected across a pure 25.0 mH inductor. Find the current through the inductor if the frequency of the source is 120/π Hz.

  1. 12 A
  2. 20 A ✓
  3. 18 A
  4. 6 A
Explanation

First law: energy is conserved. ΔU = Q – W (internal energy change = heat added minus work done by system). Heat engines convert thermal energy to mechanical work.

Second law: heat flows from hot to cold naturally. Entropy (disorder) of isolated system always increases. Efficiency of heat engine limited by temperature ratio.

Carnot efficiency = 1 – T_cold/T_hot (temperatures in Kelvin). This is maximum possible efficiency. Real engines are always less efficient due to irreversibilities.

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