Display Technologies

The Blu-ray Disc (BD) is indeed different from the traditional DVD in several ways. Firstly, the DVD supports Standard Definition video while BD supports High Definition video. This means that the quality of video that can be stored and played back on a BD is significantly higher than that on a DVD. Secondly, the BD format has several times more storage capacity compared to a DVD. This allows for more data to be stored on a single disc. However, the third statement is incorrect. The thickness of both BD and DVD is 1.2 mm, not 2.4 mm for BD as mentioned in the statement. Therefore, only the first two statements are correct.

An organic light-emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current. **Statement 1 is correct:** One of the key advantages of OLED technology is that the organic light-emitting materials can be deposited on flexible plastic or metal foil substrates, enabling the creation of flexible and foldable displays. **Statement 2 is correct:** The flexibility of OLED displays allows for the creation of roll-up or rollable displays, which can be integrated into clothing and other flexible surfaces. **Statement 3 is correct:** OLED display technology can be used to create transparent displays, where the light-emitting pixels can be made semi-transparent, allowing the display to be integrated into various surfaces and objects. Therefore, all three statements are correct.

**Statement 1 is correct.** Sodium lamps emit light in a 360-degree pattern, while LED lamps are directional. **Statement 2 is incorrect.** LED lamps generally have a longer lifespan compared to sodium lamps. **Statement 3 is correct.** Sodium lamps emit monochromatic light, whereas LED lamps offer a wider spectrum of visible light, providing significant colour advantages in street lighting.

**✅ Statement I: Correct** Rare earth elements like europium, terbium, and yttrium are essential in flat TV screens and monitors due to their role in producing vibrant colors and enhancing display quality. **✅ Statement II: Correct** These elements exhibit phosphorescence—absorbing energy and slowly emitting light—which is key to their use in color reproduction and brightness in displays. **Relationship:** Statement II explains why rare earth elements are crucial in displays, confirming the reason behind Statement I. **Therefore, both statements are correct and related.**