EMC Question of the Week: October 20, 2025
The displacement current in a transmission line flows back and forth in a direction that is ____________ relative to the direction of the wave propagation.
- parallel
- perpendicular
- circular
- at a 45° angle
Answer
The best answer is “b.” The displacement current is the time-derivative of the electric flux. In a linear dielectric, the electric flux is proportional to the electric field and is always perpendicular to the direction of the wave propagation (TEM propagation modes).
Note: The answer to this week's question appeared in the answer to last week's question about conduction currents.
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