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Electronics Engineering QUESTION #11746
Question 1
A current probe (Rogowski coil type) connected to an oscilloscope measures the inrush current of a transformer at switch-on. The integrator output of the Rogowski coil is proportional to:
  • The derivative of the current $dI/dt$
  • The instantaneous current $I(t)$✔️
  • The accumulated charge $Q = \int I\,dt$
  • The RMS value of current only
Correct Answer Explanation
A Rogowski coil produces an EMF proportional to $dI/dt$ (rate of change of current). The output is then integrated electronically to recover $I(t)$: $V_{out} \propto \int \frac{dI}{dt}\,dt = I(t)$. The result is a waveform directly proportional to the instantaneous current. Rogowski coils are valued for measuring high-frequency transient currents and large pulsed currents without iron core saturation.