Science and Technology (Part-II)

Total Questions: 50

41. What is the difference between a CFL and an LED lamp ? [2011-1]

(1) To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semi-conductor material

(2) The average life span of a CFL is much longer than that of an LED lamp

(3) A CFL is less energy-efficient as compared to an LED lamp

Which of the statements given above is/are correct?

Correct Answer: (c) 1 and 3 only
Solution:
LED BulbsCFL Bulbs
LED bulbs use light-emitting diodes to produce light when an electric current passes through them.CFL bulbs use gas-filled tubes and phosphor coatings to emit light when an electric current excites the gas.
They are more energy-efficient and consume less electricity compared to CFL bulbs.CFL bulbs are more energy-efficient than traditional incandescent bulbs but consume more electricity than LED bulbs.
LED bulbs have a longer lifespan and can last up to 25,000 to 50,000 hours, depending on the model.CFL bulbs have a shorter lifespan compared to LED bulbs and typically last between 8,000 to 15,000 hours.
They have instant full brightness when turned on, with no warm-up time required.CFL bulbs require a short warm-up period before reaching their full brightness level.
LED bulbs emit light in a specific direction, making them more suitable for focused lighting applications.CFL bulbs emit light in multiple directions, requiring reflectors or diffusers for proper light distribution.
They are available in a wide range of color temperatures, from warm white to cool daylight, allowing for customized lighting options.CFL bulbs are available in different color temperatures, but the range of options is more limited compared to LED bulbs.
LED bulbs do not contain mercury, making them safer and more environmentally friendly to use and dispose of.CFL bulbs contain a small amount of mercury and require special recycling or disposal methods to prevent environmental contamination.
They are more durable and resistant to shocks and vibrations compared to CFL bulbs.CFL bulbs are more fragile and sensitive to shocks and vibrations, which can shorten their lifespan.

42. A new optical disc format known as the Blu-ray Disc (BD) is becoming popular. In what way is it different from the traditional DVD? [2011-1]

1. DVD supports Standard Definition video while BD supports high definition video.

2. Compared to a DVD, the BD format has several times more storage capacity.

3. Thickness of BD is 2.4 mm while that of DVD is 1.2 mm.

Which of the statements given above is/are correct?

Correct Answer: (b) 1 and 2 only
Solution:Statement 3 is incorrect as the thickness of BD is 1.1 mm while that of DVD is 1.2 mm. The difference lies in capacity so statement 2 is correct. As far as statement 1 is concerned.
Both BD and DVD are optical discs, but they use different lasers:
  • DVD: Uses a red laser with a wavelength of 650 nm.
  • Blu-ray Disc (BD): Uses a blue-violet laser with a shorter wavelength of 405 nm.

The shorter wavelength of the blue-violet laser used in Blu-ray allows for a tighter focus of the laser beam. This enables the data pits and tracks on the disc to be much smaller and closer together than on a DVD. Because the data can be packed more densely on a Blu-ray Disc, it can hold significantly more information, thus supporting higher resolution video and offering greater storage capacity.
Another difference is the data layer's proximity to the surface. On a DVD, the data layer is about 0.6 mm below the surface. On a Blu-ray Disc, the data layer is much closer to the surface, protected by a thin, hard coating (often called "Durabis"). This design, combined with the shorter wavelength laser, contributes to the increased data density

43. What is "Virtual Private Network"? [2011-1]

Correct Answer: (b) It is a computer network across a public internet that provides users access to their organization's network while maintaining the security of the information transmitted.
Solution:
  • A VPN, stands for virtual private network, establishes a digital connection between your computer and a remote server owned by a VPN provider.
  • It creates a point-to-point tunnel that encrypts personal data, masks your IP address, and lets you sidestep website blocks and firewalls on the internet.
  • This ensures online experiences are private, protected, and more secure.
  • It is
    -Virtual because no physical cables are involved in the connection process.
    -Private because through this connection, no one else can see your data or browsing activity.
    -Networked because multiple devices—your computer and the VPN server—work together to maintain an established link.
  • Advantages of VPN
  • Secure your data: A VPN connection scrambles your data into code and renders it unreadable to anyone without an encryption key. It hides your browsing activity so that no one else can see it.
  • Bypass censorship and surveillance: Some regions may not have access to certain sites or services due to government restrictions, censorship, or surveillance. Location spoofing gives these users the ability to circumvent firewalls, view blocked websites, and move freely online.
  • Prevent ISP and third-party tracking: Internet service providers (ISPs) log and track your browsing history through your device's unique IP address. By routing to a remote VPN server instead of your ISP's servers, a VPN masks your IP address, prevents ISP tracking, and keeps your personal data private

44. Graphene is frequently in news recently, what is its importance? [2012-1]

1. It is a two dimensional material and has good electrical conductivity.

2. It is one of the thinnest but strongest materials tested so far.

3. It is entirely made of silicon and has high optical transparency.

4. It can be used as conducting electrodes required for touch screens. LCDs and organic LEDs.

Which of the statements given above are correct?

Correct Answer: (c) 1, 2 and 4 only
Solution:

About Graphene

  • It is an allotrope of carbon, along with diamond and graphite.
  • It is a two-dimensional material consisting of a single layer of carbon atoms arranged in a honeycomb structure.
  • The stacked form of graphene is graphite.
  • Graphene was first isolated in 2004. Since then, graphene has found hundreds of innovative applications, from sensors and electronics to energy storage and healthcare.

Graphene Properties

  • Thickness: Graphene is the world's thinnest material – it is only one atom thick, one million times thinner than a human hair.
  • Strength: It is 200 times stronger than steel but six times lighter.
  • Flexibility: It is extremely flexible and stretchable.
  • Conductivity: It is an excellent electrical and thermal conductor.
  • Transparency: It is almost perfectly transparent since it only absorbs 2% of light.
  • It is impermeable to gases, even those as light as hydrogen or helium.

45. In addition to fingerprint scanning, which of the following can be used in the biometric identification of a person? [2014-1]

1. Iris scanning

2. Retinal scanning

3. Voice recognition

Select the correct answer using the code given below.

Correct Answer: (d) 1, 2 and 3
Solution:Biometrics identification is used in computer science as a form of identification and access control. Biometric identifiers are the distinctive, measurable characteristics used to label individuals. Biometric identifiers are categorized as physiological versus behavioral characteristics.

Physiological Biometric identifiers are fingerprint, palm veins, face recognition, DNA, palm print, hand geometry, iris recognition, retina and odour/scent. Behavioral identifiers are typing rhythm, gait and voice.

46. With reference to 'Near Field Communication (NFC) Technology', which of the following statements is/are correct? [2015-1]

1. It is a contactless communication technology that uses electromagnetic radio fields.

2. NFC is designed for use by devices which can be at a distance of even a metre from each other

3. NFC can use encryption when sending sensitive information.

Select the correct answer using the code given below.

Correct Answer: (c) 1 and 3 only
Solution:
  • Near-field communication (NFC) is a short-range wireless technology that makes your smartphone, tablet, wearables, payment cards, and other devices even smarter. Near-field communication is the ultimate in connectivity.
  • Near-field communication transmits data through electromagnetic radio fields to enable two devices to communicate with each other. So, statement 1 is correct.
  • To work, both devices must contain NFC chips, as transactions take place within a very short distance. NFC-enabled devices must be either physically touching or within a few centimeters of each other for data transfer to occur. So, statement 2 is not correct.
  • NFC uses 128-bit or higher encryption to guarantee security and privacy of transactions. Because NFC uses tokenization instead of storing credit card information, for example, no retailer can see your credit card number. So, statement 3 is correct.

47. In the context of modern scientific research, consider the following statements about 'Ice Cube', a particle detector located at South pole, which was recently in the news: [2015-1]

1. It is the world's largest neutrino detector, encompassing a cubic kilo metre of ice.

2. It is a powerful telescope to search for dark matter.

3. It is buried deep in the ice.

Which of the statements given above is/are correct?

Correct Answer: (d) 1, 2 and 3
Solution:

About IceCube Neutrino Observatory

  • It is a device at the earth's South Pole that detects subatomic particles called neutrinos.
  • It was built and is maintained by the IceCube Collaboration, which consists of many universities worldwide led by the University of Wisconsin, Madison.
  • It consists of thousands of sensors buried more than 1.4 km beneath the ice plus multiple detectors above the surface.
  • IceCube is the world's biggest 'neutrino telescope'; its sensors are distributed throughout a cubic kilometre of ice.

Working

  • When a neutrino interacts with the ice surrounding the sensors, it may produce some charged particles and some radiation.
  • The sensors detect the radiation to infer the detection of a neutrino and use the radiation's properties to understand more about the particle.
  • Neutrinos come in different types. IceCube can identify some of them in real-time.
  • For others, IceCube collects data for many years and scientists then comb through them to find neutrino interaction events.

48. What is 'Greased Lightning-10 (GL-10)', recently in the news? [2016-1]

Correct Answer: (a) Electric plane tested by NASA
Solution:The 'Greased Lightening-10' (GL-10) is a 28 kg with 10 engines that can take off and land like a helicopter and fly efficiently like an aircraft. It is a battery-powered drone prototype plane designed by NASA.

49. With reference to 'Li-Fi', recently in the news, which of the following statements is/are correct? [2016-1]

1. It uses light as the medium for high-speed data transmission.

2. It is a wireless technology and is several times faster than 'Wi-Fi'.

Select the correct answer using the code given below.

Correct Answer: (c) Both 1 and 2
Solution:(i) This OWC technology uses light from light-emitting diodes (LEDs) as a medium to deliver networked, mobile, high-speed communication in a similar manner to Wi-Fi. It is a bidirectional, high-speed and fully networked wireless communication technology similar to Wi-Fi.

(ii) Li-fi gives data transfer rate of 10 gigabytes per second. So 1st statement is right. Li-Fi device circulates data via LEDs that emit an intermittent flicker at a speed imperceptible to the human eye. So, 2nd statement also right.

50. What is the purpose of 'evolved Laser Interferometer Space Antenna (ELISA)' project? [2017-1]

Correct Answer: (b) To detect gravitational waves
Solution:
  • The evolved Laser Interfermoter Space Antenna (eLISA) is a mission aiming at exploring the Gravitational Universe from space for the first time.
  • It involves scientists from eight European countries – Denmark, France, Germany, Italy, The Netherlands, Spain, Switzerland, and the UK – as well as the support of several US-based ones.
  • The eLISA mission consists of a "Mother" and two "Daughter" spacecrafts. These will orbit the Sun in a triangular configuration. The three satellites will form a precision interferometer, with the two Daughter spacecrafts connected to the Mother one by 1 million km long laser beams. This interferometer will be capable of detecting gravitational waves at frequencies in the range of 0.1 mHz to 1 Hz.
  • Such a frequency interval is not accessible on Earth due to arm length limitations and to noise caused by the terrestrial gravity gradient noise: in this sense, eLISA will complement the efforts of ground-based gravitational-wave detectors.