Which two of the following are means in which radiated interference primarily enters electronic devices? (Select two options.)

Question

Options

• AProximity to interfering sources
• BMissing or inadequate optical connections
• CMissing or inadequate device or cable shielding
• DInterface designs
• EInput signal lines

• A
  78% (28)
• B
  6% (2)
• D
  3% (1)
• E
  14% (5)

Explanation

Radiated interference enters devices primarily through proximity to interfering sources (A) - the closer a device is to an emitter (like a motor or transmitter), the stronger the electromagnetic field it experiences, increasing susceptibility. Missing or inadequate shielding (C) is the other key pathway: without proper metallic enclosures or shielded cables, radiated EMI passes directly into the device or travels along unprotected conductors into sensitive circuitry.

The distractors are wrong for these reasons:

• B (optical connections) - fiber optic connections are inherently immune to EMI, so this is irrelevant to radiated interference.
• D (interface designs) - while poor design can cause issues, this is too vague and describes a conducted or design-level problem, not a primary radiated entry mechanism.
• E (input signal lines) - signal lines can carry interference, but that describes conducted interference, not radiated interference entering the device.

Memory tip: Think "R.A.S." - Radiated EMI needs two things to enter: Access (proximity) and a gap in your Shield. If it's close enough and unshielded, it gets in.

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