I believe this answer is incorrect. The cable isn't supposed to be run parallel to electrical conduit. But perpendicular should be okay. So B would make more sense as being the problem, since the entire building is affected at night.

I am fairly certain you are **supposed** to run network cable perpendicular to the electrical conduit to preserve communication and minimize disruption. I think the answer is "B" as well.

B: - fluorescent lights (EMI) - network dispruption occurs only certain hours, when wings of the building have lack of natural light -> fluorescent lights are on -> EMI disrupts network. If it was because of the perpendicular wiring, then network would've been down constantly.

Answer here is B. The key is when the users are experiencing the connectivity issues. During the morning the users on the west side have having issues. The east side of the building is receiving natural light and the lights are off (no EMI). Later on in the day, east side of the building is having issues because natural light has shifted to west side of building and east side is getting hit with EMI due to the lights being on. At night, the entire building has problems because lights are on in the entire building.

certain hours

I go for C. Fluorescent light can make EMI on the wires but it has been said the wires are close to the lamps.

Fluorescent lights can be a significant source of EMI due to their starting principle. In order to create a spark across the florescent tube there needs to be 500V and more (depending on technology) to start. This voltage is dissipated through air with by a fluorescent light starter that is basically an interference source for all surrounding equipment. An Electro Magnetic Interference source can be anything that carries electricity; a broken fluorescent starter, a grounded machinery, a cable with damaged insulation or a new smart watch.

Perpendicular wiring can cause EMI effects much more than lights. You can check the right-hand rule. https://physics.stackexchange.com/questions/395851/left-or-right-hand-rule/395881

I'm gonna go with B here

the answer IS C but for a dumb reason. When a building is equip with sensor activated lights that turn on at night, those lights are generally OUTSIDE of the building. So the lights that are outside cant really interfere with network cables that are INSIDE the building. the question never states that the lights are outside they somehow expect you to assume that yourself through logic. This question does not give you all of the information that you need to answer it.

It states EMI from the light itself it doesn't mention the nework wirings relationship to the lights in this answer, to select this we would have to make an assumption the cable runs by lights. They state the network cable is perpendicular which means they are crossing at right angles. When lights are idle at the times given there is no current flowing so there isnt an impact of the wiring layout, when the light is activated the current flows ans starts interfering with the signal flowing through the network cable. The answer is correct in my opionion

I believe the most logical answer is C. The problem persists when the light sensors toggle on the florescent lights, creating a flow of alternating current. The current will cause EMI with the network cable's transmissions.

I think the answer here is meant to be C, but the wording of the answer is wrong.

My professor, holding advanced degrees, says given answer is correct! Florescent affects wireless. ANd electricity is like water in a pipe. Not flowing, it dont cause problems. Flowing it causes problems. It would flow in mornings and evenings.

A. Light sensors are interfering with the network. When the sun goes up and the area will not be hit by the sun rays the light sensor will trigger ON. As the sun change phase the light sensor started to OFF if the sensor will not be struck from the rays. At night the entire building has no connection because the light sensors are all functioning due to the absence of sunlight.

B is the right answer.

Answer should be B, if wiring was runned perpendicular to electrical cabling, the issue should not always manifest during sometime, it should manifest always because the sensors are always ON to identify if they need to turn the lights ON or OFF.