Which of the following is a reason to use shielded wire?

• A. To improve signal strength
• B. To prevent coupling of unwanted signals
• C. To reduce weight of the wiring
• D. To lower production costs

Answer: (B)

Using shielded wire is primarily effective in preventing the coupling of unwanted signals. Shielding involves enclosing the conductor with a conductive material that acts as a barrier against electromagnetic interference (EMI) and radio frequency interference (RFI). In environments where there is a high level of electrical noise, such as in urban areas or near other electronic devices, shielded wire helps maintain the integrity of the signal by minimizing noise and crosstalk from adjacent cables and systems.

This shielding is crucial for applications in ham radio and other communication systems, where clear signal transmission is essential for effective operation. The shield absorbs and redirects interference away from the signal-carrying conductor, ensuring that the information transmitted is as clear as possible.

Other options do not align with the primary function of shielded wire. Improving signal strength typically involves ensuring proper design in the whole system rather than just using shielded wire. Reducing weight of wiring doesn't relate directly to shielding and is not a characteristic typically associated with shielded wires, which can sometimes actually be heavier due to the additional materials. Lowering production costs is generally not the aim when using shielded wire, as the materials and creation of shielded wire can increase costs compared to unshielded options.