Day-523 | Daily MCQs | UPSC Prelims | CURRENT DEVELOPMENTS

Answer: A
Explanation:
Considered the next big transition in display technology, microLEDs are self-illuminating diodes that have brighter and better colour reproduction than Organic Light Emitting Diode (OLED) display technology.
● Statement 1 is correct: OLEDs use tiny sub-pixels made from organic emissive materials. Micro-LEDs are somewhat similar – but with an inorganic LED structure. Compared to OLEDs, Micro-LEDs promise to be much more efficient and bright, more durable (higher lifetime) and with a higher color gamut, mostly due to the superior performance of LEDs over their organic counterparts.

● Statement 2 is incorrect: microLED has higher power efficiency but lower response time than OLED displays.
● Statement 3 is incorrect: microLED has higher brightness and sunlight visibility than OLED displays.
About Micro-LED:
● Micro-LED (also known as mLED or µLED) is a display technology that is based on tiny (hence, micro) LED devices that are used to directly create color pixels. Micro-LED displays have the potential to create highly efficient and great looking flexible displays, to challenge the current high-end OLED displays.
Micro-LED vs LED:
● Current so-called LED displays are actually LCD displays that use LED as backlighting units – which are always on with a liquid-crystal layer that is used to create the actual image (i.e. block the light where needed). This complicated LCD structure results in a device with serious image quality drawbacks (mainly a low response time and relatively poor contrast ratio) and also difficulties in achieving flexibility and high-quality transparency.
Micro-LED vs OLED:
● OLEDs use tiny sub-pixels made from organic emissive materials. Micro-LEDs are somewhat similar – but with an inorganic LED structure. Compared to OLEDs, Micro-LEDs promise to be much more efficient and bright, more durable (higher lifetime) and with a higher color gamut. Micro-LEDs are based on well-established LED devices, which means that it could potentially be a technology that is relatively easy to scale up.

Answer: B
Explanation:
● After more than three years, a controversial Trump-era immigration policy known as Title 42 is set to expire on 11 May.
Option(b) is correct:
● ‘Title 42’ policy came to the forefront of US immigration policy in March 2020, when the Trump administration invoked the statute to stop the spread of Covid-19 across its borders. With Title 42 in place, US authorities were able to swiftly expel would-be migrants attempting to cross the border from Mexico – including those seeking humanitarian asylum – using the pandemic as justification.

Answer: B
Explanation:
Finland has installed the world’s first sand battery that can store heat from renewable energy sources for months.
● Statement 1 is incorrect: Sand-based heat storages can store several times the amount of energy that can be stored in a water tank of a similar size. Sand can be heated up to 600 degrees Celsius (°C), whereas water starts to boil at 100°C. It also has low heat conductivity, which reduces energy loss.
● Statement 2 is correct: It can be used for a centralised heating network that can keep buildings and public water systems warm.
● Statement 3 is correct: Finland is the first country to install Sand Batteries.

Answer: C
Explanation:
U.S. officials said that a Chinese “surveillance balloon” has been flying over the United States for several days. It drifted across the US and flew far higher than passenger jets.
● Statement 1 is incorrect: High Altitude Surveillance Balloons usually placed in the stratosphere.
● Statement 2 is correct: The advantages of balloons over satellites include the ability to scan wide swathes of territory from closer in, and to be able to spend more time over a target area.
● Statement 3 is correct: It is powered by the Solar energy panels attached to it.
● Statement 4 is correct: It randomly moves on the basis of wind direction at a particular altitude.

Answer: B
Explanation:
● The Union Minister of Science & Technology inaugurated the efficient Phytorid Technology Sewage Treatment Plant (STP) at CSIR-NCL at Pune which is a self sustainable technology for wastewater treatment that works on the principle of natural wetland.
Option(b) is correct:
● The phytorid technology treatment is a subsurface flow type in which wastewater is applied to a cell / system filled with porous media such as crushed bricks, gravel and stones. The hydraulics is maintained in such a manner that wastewater does not rise to the surface retaining a free board at the top of the filled media.