Which of the following is not a guided transmission line?Twisted pairCoaxial cableLaser beamOptical fiber

To determine which of the following options is not a guided transmission line, let's first understand what a guided transmission line is. Guided transmission lines are physical structures that guide electromagnetic waves from one point to another. Common examples include twisted pair cables, coaxial cables, and optical fibers, where the transmission medium confines the signal within defined physical boundaries.

1. Twisted Pair: A type of cable that consists of pairs of wires twisted together to reduce electromagnetic interference. It is a guided transmission line.

2. Coaxial Cable: A cable with an inner conductor surrounded by a concentric conducting shield, guiding signals very effectively. It is also a guided transmission line.

3. Optical Fiber: A technology that uses light to transmit data through a glass or plastic fiber, confining light to the core. This is definitely a guided transmission line as well.

4. Laser Beam: A coherent beam of light emitted by a laser. Unlike the other options, a laser beam travels through space without a physical transmission medium to guide it, hence it is not a guided transmission line.

Final Answer

Laser beam is not a guided transmission line.