Day-609 | Daily MCQs | UPSC Prelims | GENERAL SCIENCE AND TECHNOLOGICAL DEVELOPMENTS

Answer: C
Explanation
Although solar wind, solar flare and coronal mass ejection are interrelated they all describe the sun’s activity. Only the frequency of occurrence and intensity differs.
Statement 1 is correct: Solar winds are a stream of plasma particles that are ejected from the Sun’s atmosphere. They are caused by the interaction of plasma with gases present in the earth’s ionosphere. This produces a brilliant display of colours in the night sky in polar regions generally known as Auroras. The solar wind is a continual stream of protons and electrons from the sun’s outermost atmosphere — the corona. These charged particles breeze through the solar system at speeds ranging between 400km per sec and 800km per sec.
Statement 2 is correct: Solar flares are an intense burst of radiation that is caused by the release of magnetic energy from sunspots. They can be damaging to satellites and electronics on Earth.
Statement 3 is correct: Coronal Mass Ejections (CME) are sudden, terribly violent ejections of billions of tons of plasma from the Corona or the Sun’s outer atmosphere. They can cause geomagnetic turbulence and damage the Earth’s magnetic field.

Answer: A
Explanation:
Context: The International Thermonuclear Experimental Reactor (ITER) is already billions of dollars over budget and decades behind schedule. Not even its leaders can say how much more money and time it will take to complete. It run the risk of turning into one of the largest scientific disaster in the history of mankind. ITER is supposed to help humanity achieve the dream of a world powered not by fossil fuels but by fusion energy, the same process that makes the stars shine.
Explanation
Statement 1 is CORRECT: Fusion reactions is intrinsically safe and is not expected to produce high activity or long-lived nuclear waste. Furthermore, as the fusion process is difficult to start and maintain, there is no risk of a runaway reaction and meltdown.
Statement 2 is CORRECT and is CORRECT explanation of Statement 1: Fusion can only occur under strict operational conditions, outside of which (in the case of an accident or system failure, for example), the plasma will naturally terminate, lose its energy very quickly and extinguish before any sustained damage is done to the reactor. Importantly, nuclear fusion — just like fission — does not emit carbon dioxide or other greenhouse gases into the atmosphere, so it could be a long-term source of low-carbon electricity in future.

Answer: B
Explanation:
The Dual Nature of matter and the dual nature of radiation were ground-breaking physics notions. Scientists discovered wave-particle duality, or the dual nature of matter and radiation. Everything is made up of waves and particles.
What is a Photon?
A photon is the smallest discrete amount of electromagnetic energy, also known as a quantum. It’s the fundamental unit of all light.
Photons have the following basic properties:
The quantity of photons crossing an area per unit time increases as light intensity increases. It has no effect on the radiation’s energy.
Electric and magnetic fields have no effect on a photon. It has no electrical charge.
A photon is massless.
It’s a sturdily constructed particle.
When radiation is emitted or absorbed, photons can be generated or destroyed.
During a photon-electron collision, the whole energy and momentum are conserved.
A photon is incapable of decay on its own.
A photon’s energy can be transferred when it interacts with other particles.

Answer: D
Explanation:
The basic purpose of LiDAR and RADAR is the same – detecting the presence and volume of distant objects – it is essential to understand the difference between these two technologies.
Light Detection and Ranging (LiDAR) is a light-based remote sensing technology. By having a LiDAR with a 360° viewing angle it is possible to obtain a point cloud of the environment. Then, a specific software makes a 3D image that reproduces the shape around the LiDAR with a precise position in space.
The RADAR system works in much the same way as LiDAR, with the big difference that it uses radio waves instead of laser or LED light. It transmits radio waves from a rotating or fixed antenna and measures the time of flight of the reflected signal.
With its wavelength, the RADAR can detect objects at long distance and through fog or clouds. But its lateral resolution is limited by the size of the antenna. The resolution of standard RADAR is several meters at 100 meters.
LiDAR is a compact solution that enables a high level of accuracy for 3D mapping. At 100 meters, LiDAR systems have a resolution of a few centimetres.
This is why LiDAR is used for laser altimetry and contour mapping. Radar, on the other hand, is used for aircraft anti-collision systems, air traffic control or radar astronomy.

Answer: B
Explanation:
Gravity is the force by which a planet or other body draws objects toward its centre. The force of gravity keeps all the planets in orbit around the sun.
Anything that has mass also has gravity. Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is.
Earth’s gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body. That’s what gives you weight. And if you were on a planet with less mass than Earth, you would weigh less than you do here.
Gravity is the force by which a planet or other body draws objects toward its centre. The force of gravity keeps all the planets in orbit around the sun.

Gravity in our universe
Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity creates stars and planets by pulling together the material from which they are made. It not only pulls on mass but also on light. Albert Einstein discovered this principle. If you shine a flashlight upwards, the light will grow imperceptibly redder as gravity pulls it. You can’t see the change with your eyes, but scientists can measure it.