Q. With reference to Visible Light Communication (VLC) technology, which of the following statements are correct? - VLC uses electromagnetic spectrum wavelengths 375 to 780 nm.
- VLC is known as long-range optical wireless communication.
- VLC can transmit large amounts of data faster than Bluetooth.
- VLC has no electromagnetic interference.
Select the correct answer using the code given below: (UPSC Prelims 2020)
Answer:
1, 3 and 4 only
Notes: The correct answer is
[C] 1, 3 and 4 only. Visible Light Communication (VLC) is a wireless method that uses light emissions from LEDs to transmit data.
- Wavelength Range (Statement 1 – Correct): VLC operates in the visible light portion of the electromagnetic spectrum, typically ranging from 375 nm to 780 nm (violet to red).
- Data Transmission Speed (Statement 3 – Correct): Because the visible light spectrum has a much higher bandwidth than the radio frequency spectrum used by Bluetooth or Wi-Fi, VLC can transmit data at much higher speeds, reaching several gigabits per second.
- Electromagnetic Interference (Statement 4 – Correct): Unlike Wi-Fi or Bluetooth, which use radio waves, VLC uses light. Therefore, it does not interfere with radio frequency-based equipment, making it ideal for sensitive environments like hospitals or aircraft cabins.
- Range (Statement 2 – Incorrect): VLC is specifically known as a short-range optical wireless communication technology. Since light cannot penetrate opaque objects (like walls) and its intensity diminishes quickly over distance, its range is limited compared to long-range radio technologies.
VLC is the foundational technology behind
Li-Fi (Light Fidelity), which aims to provide high-speed internet through existing indoor lighting infrastructure.