One way to avoid EMI problems is to _. Select one: a. run low-voltage cable close to power cables b. use fluorescent lights c. use ungrounded metal pathways d. terminate unused conductors at both ends
The correct answer and explanation is:
Correct answer: d. terminate unused conductors at both ends
Explanation:
Electromagnetic Interference (EMI) refers to the unwanted disturbance caused by electromagnetic fields that can disrupt the performance of electronic devices. EMI can be introduced from various sources like power lines, motors, lighting systems (especially fluorescent), and even other data cables. Managing EMI is crucial in environments with sensitive electronics or data communications.
Option d: Terminate unused conductors at both ends – This is the correct method to avoid EMI problems. When conductors (wires or cables) are not terminated properly, they can act like antennas, unintentionally radiating or receiving electromagnetic noise. This can significantly increase EMI in a system. By properly terminating both ends of unused conductors, you minimize the risk of them picking up or emitting EMI. Termination usually involves connecting the conductor to ground or using resistive loads to prevent signal reflection and stray radiation.
Why the other options are incorrect:
- a. Run low-voltage cable close to power cables – This is bad practice. Running data or low-voltage communication cables near high-voltage power cables increases the chance of induced EMI, as power lines generate strong electromagnetic fields. Proper separation or shielding is essential to avoid interference.
- b. Use fluorescent lights – Fluorescent lighting is a known source of EMI. The ballasts and switching mechanisms inside can emit high-frequency noise that may interfere with nearby electronic devices, especially radios and sensitive instrumentation.
- c. Use ungrounded metal pathways – Ungrounded metal components can accumulate and radiate EMI. Proper grounding of metal conduits and pathways is necessary to safely dissipate electromagnetic energy and prevent it from affecting nearby circuits.
In conclusion, proper termination of unused conductors is a simple and effective technique in managing EMI, especially in structured cabling and communication systems.