Red Seal Electrician Practice
Signalling and communicationQuestion 240 of 1506

Why does a clean 10 kHz square wave look rounded at the far end of a long two-wire cable?

  1. A square wave has no frequency content above 10 kHz
  2. A square wave is just one pure 10 kHz sine wave
  3. The cable adds a steady DC voltage to the signal
  4. The cable distorts its many higher-frequency parts
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Correct answer: The cable distorts its many higher-frequency parts

A square wave is a stack of sine waves that reach up to hundreds of kHz. The cable capacitance and inductance treat them unequally, so the sharp edges round off.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 14.4: Electrical Signal Types

Practice signalling and communication

Questions last reviewed: 18 October 2026