<閱讀測驗>[題組:第40題到第43題]Flickering lamps can induce headaches. But if the flickering happens millions of times a second-far faster than the eye can see or the brain process-then it might be harnessed to do something useful, like transmitting data. This is the idea behind Li-Fi, or Light Fidelity. The term Li-Fi was coined by University of Edinburgh Professor Harald Haas in a 2011 TED Talk, where he introduced the idea of “wireless data from every light.” Today, Li-Fi has developed into a wireless technology that allows data to be sent at high speeds, working with light-emitting diodes (LEDs), an increasingly popular way to illuminate public areas and homes. Using LED lights as networking devices for data transmission, Li-Fi has several advantages over WiFi (Wireless Fidelity). First, Li-Fi allows for greater security on local networks, as light cannot penetrate walls or doors, unlike radio waves used in Wi-Fi. As long as transparent materials like glass windows are covered, access to a Li-Fi channel is limited to devices inside the room, ensuring that signals cannot be hacked from remote locations. Also, Li-Fi can operate in electromagnetic sensitive areas such as aircraft cabins, hospitals, and nuclear power plants, for light does not interfere with radio signals. The most significant advantage of Li-Fi is speed. Researchers have achieved speeds of 224 gigabits per second in lab conditions, much faster than Wi-Fi broadband. How could Li-Fi enrich daily life? Anywhere there is LED lighting, there is an opportunity for Li-Fi enabled applications. Li-Fi-enabled street lights could provide internet access to mobile phones, making walking at night safer. The LED bulbs in traffic lights could provide drivers with weather conditions and traffic updates. Li-Fi could help with tourism by providing an easier access to local information. At home, smart light could also provide parents with solutions to their children’s Internet addiction: Just turn off the lights and you’ve turned off their access. When 14 billion light bulbs mean 14 billion potential transmitters of wireless data, a cleaner, a greener, and even a brighter future is on the way. 40. What is this passage mainly about? (A) A new design in lighting. (B) Wireless transmission through illumination. (C) Radio interference in public areas. (D) Potential applications of Li-Fi for military use.
