UPSC Essentials | Daily subject-wise quiz : Science and Technology MCQs on semiconductors, Speed of Light and more (Week 127)

QUESTION 1

With reference to the Speed of Light, consider the following statements:

1. The speed of light is highest in a vacuum.

2. The speed of light is different in different directions.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Explanation

— At exactly 299,792 kilometers per second (about 186,000 miles per second), the speed of light in a vacuum is the fastest anything can travel in the universe. Hence, statement 1 is correct.

— Albert Einstein built his theory of relativity around this principle: no information or material object can exceed the speed of light.

— The first real proof that light’s speed was finite came in 1676. Danish astronomer Ole Rømer was observing the eclipses of Io, one of Jupiter’s moons. He noticed the timings of these eclipses varied depending on Earth’s position in its orbit: when Earth was moving away from Jupiter, Io seemed to be “late,” and when moving closer, “early.”

— Two centuries later, French physicist Hippolyte Fizeau made the first precise terrestrial measurement. In 1849, he sent a beam of light through the gaps of a rapidly spinning cogwheel to a mirror eight kilometers away. When the returning beam was blocked by the next tooth, he could calculate the travel time. His result — about 313,000 km/s — was remarkably close to today’s accepted value.

— The speed of light was the same in all directions. Hence, statement 2 is not correct.

Therefore, option (a) is the correct answer.

QUESTION 2

With reference to the undersea cables, consider the following statements:

1. These are essentially wires laid on the ocean floor for communications.

2. These cables do not have any threat from natural disasters like earthquakes.

3. Once laid, repairing is not possible in undersea cables.

4. These are also known as submarine cables.

How many of the statements given above are correct?

(a) Only one

(b) Only two

(c) Only three

(d) All four

Explanation

— Some undersea cables in the Red Sea were reportedly cut recently, sparking internet disruptions in India, Pakistan and other parts of Asia.

— Also called submarine cables, these are essentially wires laid on the ocean floor for communications, much like on land. It is through wires that data — images, voice, text — is transferred among devices. Hence, statements 1 and 4 are correct.

— Underwater cables were the next logical step after wires were laid on land in countries like the United Kingdom to transmit electrical telegraphic messages. To share information across continents, cables had to be connected via oceans, and this was initially done for relatively short distances.

— According to the US National Oceanic and Atmospheric Administration (NOAA), submarine cables can be buried or not buried, depending on the depth. At more than 2,000 metres below sea level, they are simply laid, as there is a limited chance of harm due to human activities like fishing nets or big trawlers.

— There are many threats to these cables, from earthquakes to strong ocean currents to anchors dropped from ships. Hence, statement 2 is not correct.

— Repairing is a difficult and expensive task, where divers are sent to the source or the cables are brought above ground and then fixed. Hence, statement 3 is not correct.

— With time, fibre optic cables came to be preferred, as they can transfer data much faster and efficiently. These are extremely thin wires (less than the thickness of a strand of human hair) made of glass or plastic. Several layers of material cover the wires for protection and to ensure that light travels rapidly. These include polythene, copper, steel, and petroleum jelly.

Therefore, option (b) is the correct answer.

QUESTION 3

Sapphire Canyon is:

(a) a sample taken from Mars

(b) a canyon discovered on the far side of the Pacific Ocean

(c) a newly found trench in the Atlantic Ocean

(d) a mineral deposit in the Arctic region of Earth

Explanation

— National Aeronautics and Space Administration (Nasa) officials will discuss a discovery related to a special sample that the Perseverance rover found on Mars.

— According to the announcement, the rock is known as ‘Sapphire Canyon’ and originates from ‘Neretva Vallis’, described as a “river valley carved by water rushing into Jezero Crater long ago”.

Therefore, option (a) is the correct answer.

QUESTION 4

With reference to the semiconductors, consider the following statements:

1. In their natural state, semiconductors are strong conductors of electricity.

2. Adding phosphorus to semiconducting materials, such as silicon and germanium, allows the flow of a negative current.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Explanation

— Union IT Minister Ashwini Vaishnaw presented India’s first fully indigenous microprocessor — a type of semiconductor chip — to Prime Minister Narendra Modi at Semicon India 2025 on September 2. The chip, called Vikram 3201, has been developed by the semiconductor laboratory of the Indian Space Research Organisation (ISRO).

— Semiconductors are unique, in that most materials are either conductors — which let electric current flow — or insulators — which block electricity. For instance, a copper wire is a conductor, while glass is an insulator.

— Semiconductors, however, are different. Although in their natural state, semiconductors are a weak conductor of electricity, when certain materials are added to them and an electric field is applied, current can start to flow. Adding phosphorus to semiconducting materials, such as silicon and germanium, for example, allows the flow of a negative current. Hence, statement 1 is not correct and statement 2 is correct.

Therefore, option (b) is the correct answer.

QUESTION 5

With reference to the proteins, consider the following statements:

1. They are made of a combination of different kinds of amino acids.

2. The structure and function of the protein are governed by the amino acids present in it.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Explanation

— The recent emergence of large language models (LLMs) has revolutionised the research on proteins — the microscopic mechanisms that are involved in virtually every important activity happening inside all living things. Scientists use a version of LLM for various tasks, such as predicting the structure or function of a protein, which contributes to the development of drugs and vaccines.

— The LLMs used for protein research are known as protein language models (pLMs). Unlike the usual LLMs, which are trained on English words, pLMs are trained on protein sequences — the linear, specific order of one-dimensional amino acids that are linked together to form a three-dimensional protein.

— Typically, proteins are made of a combination of 20 different kinds of amino acids, and the structure and function of each protein are governed by the arrangement of the various amino acids in it. For instance, antibody proteins fold into shapes that help them to identify and target foreign bodies, like when a key fits into a lock. Hence, statements 1 and 2 are correct.

Therefore, option (c) is the correct answer.

Previous Daily Subject-Wise-Quiz

Daily Subject-wise quiz — History, Culture, and Social Issues (Week 124)

Daily subject-wise quiz — Polity and Governance (Week 127)

Daily subject-wise quiz —  Science and Technology (Week 126)

Daily subject-wise quiz — Economy (Week 126)

Daily subject-wise quiz — Environment and Geography (Week 126)

Daily subject-wise quiz – International Relations (Week 126)

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