41. Consider the following statements regarding Overhauser Magnetometer:
- Overhauser Magnetometer is used in international space programs.
- The Indian Institute of Geomagnetism (IIG) has developed the Overhauser Magnetometer.
Which of the statements given above is / are correct?
[A] Only 1
[B] Only 2
[C] Neither 1 nor 2
[D] Both 1 and 2
Show Answer
Correct Answer: D [Both 1 and 2]
Notes:
The Overhauser Magnetometer is indeed widely used in international space programs and magnetic observatories due to its high accuracy. The Indian Institute of Geomagnetism (IIG) has successfully developed this magnetometer, which was previously imported, enhancing India's self-reliance in geomagnetic research technologies and reducing related costs.
42. Consider the following statements about neutrinos:
- Neutrinos are subatomic particles with no electrical charge.
- Neutrinos are exceptionally difficult to detect due to their weak interactions with matter.
- Neutrinos are produced as a by-product when neutrons separate into protons and electrons in nuclear reactors.
Which of the above statements is / are correct?
[A] Only 1
[B] Only 2 and 3
[C] Only 1 and 2
[D] 1, 2 and 3
Show Answer
Correct Answer: C [Only 1 and 2]
Notes:
Statements 1 and 2 are correct: Neutrinos are neutral subatomic particles with very small mass and are extremely hard to detect as they interact weakly with matter. However, statement 3 is incorrect, as neutrinos, not neutrons, are produced when neutrons decay into protons and electrons in processes such as beta decay, which occurs in reactors.
43. In the context of astronomical phenomena, consider the following statements:
- A ‘planet parade’ occurs when multiple planets are visible in the night sky simultaneously.
- The last occurrence of a full ‘planet parade’ was in May-June 2024.
- Mercury is the only planet that requires a telescope to be seen from Earth.
- Planets do not twinkle, while stars do, due to atmospheric turbulence.
How many of the above statements are correct?
[A] Only one
[B] Only two
[C] Only three
[D] All four
Show Answer
Correct Answer: B [Only two]
Notes:
- A ‘planet parade’ occurs when multiple planets are visible in the night sky simultaneously: This is correct; it describes a common astronomical phenomenon.
- The last occurrence of a full ‘planet parade’ was in May-June 2024: This is incorrect; the last full parade was actually earlier.
- Mercury is the only planet that requires a telescope to be seen from Earth: This is incorrect; several planets can be seen without a telescope.
- Planets do not twinkle, while stars do, due to atmospheric turbulence: This is correct; planets maintain a steady brightness compared to stars.
Thus, two statements are correct.
44. Consider the following statements about nuclear fusion:
- Nuclear fusion happens when two heavy atomic nuclei merge to form a lighter nucleus, releasing energy.
- It requires extremely high temperatures to overcome electrostatic repulsion between nuclei.
- Fusion energy produces minimal long-lived radioactive waste, unlike fission.
How many of the above statements are incorrect?
[A] Only one
[B] Only two
[C] All three
[D] None
Show Answer
Correct Answer: B [Only two]
Notes:
- Nuclear fusion happens when two heavy atomic nuclei merge to form a lighter nucleus, releasing energy. Incorrect: Nuclear fusion involves the merging of light atomic nuclei (such as hydrogen isotopes deuterium and tritium) to form a heavier nucleus (helium), releasing a vast amount of energy. Unlike nuclear fission, fusion does not involve heavy nuclei.
- It requires extremely high temperatures to overcome electrostatic repulsion between nuclei. Correct: Fusion requires extremely high temperatures (over 100 million Kelvin) to overcome the Coulomb barrier, which is the electrostatic repulsion between positively charged nuclei.
- Fusion energy produces minimal long-lived radioactive waste, unlike fission. Incorrect: Unlike nuclear fission, fusion does not generate long-lived radioactive waste. The main byproduct of fusion is helium, which is non-radioactive. Although fusion reactions involving tritium can produce some radioactive materials, their half-life is much shorter than that of fission waste.
45. Consider the following:
- Photoelectric effect
- Brownian motion
- Theory of relativity
Which of the above phenomena were explained by Albert Einstein in 1905, his “Annus Mirabilis” year?
[A] Only 1 and 2
[B] 2 and 3 only
[C] 1, 2 and 3
[D] 1 and 3 only
Show Answer
Correct Answer: C [1, 2 and 3]
Notes:
In 1905, known as his “Annus Mirabilis”, Einstein published pathbreaking papers explaining the photoelectric effect, Brownian motion, and special relativity. Each work reshaped scientific understanding—in quantum physics and relativity. This means statements 1, 2, and 3 were all explained by Einstein in that year, making all options correct.
46. Which of the following pairs of physicists and their landmark contributions are correctly matched?
- Michael Faraday → Electromagnetic induction
- Heinrich Hertz → Experimental proof of electromagnetic waves
- Enrico Fermi → Development of nuclear reactor
Select the correct option from the codes given below:
[A] Only 1 and 2
[B] Only 2 and 3
[C] 1, 2, and 3
[D] Only 1 and 3
Show Answer
Correct Answer: C [1, 2, and 3]
Notes:
Michael Faraday discovered electromagnetic induction in 1831, establishing the foundation for electric generators. Heinrich Hertz experimentally validated the existence of electromagnetic waves as predicted by Maxwell. Enrico Fermi led the development of the first controlled nuclear reactor in 1942. All three contributions are accurately matched with the respective scientists.
47. Why do loaded trucks use more fuel at constant speed on a plain road?
[A] Because rolling friction increases with load
[B] Because more work is done against gravity
[C] Because velocity increases with load
[D] Because acceleration is greater with load
Show Answer
Correct Answer: A [Because rolling friction increases with load]
Notes:
Heavier loads increase the normal force on truck tyres, raising rolling friction. Overcoming this higher friction requires more fuel, even at constant speed and on level roads. Neither gravity nor acceleration are responsible for this increased fuel usage on plains.
48. Which of the following phenomena involve reduction of surface tension by alcohol or detergents?
- Ink spreading uniformly on paper
- Paint spreading easily on walls
- Soapy bubbles forming larger surfaces
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: D [1, 2 & 3]
Notes:
Alcohol, detergents, and soaps act as surfactants by reducing surface tension. This allows ink and paint to spread more evenly and soapy water to form larger, stable bubbles. All three given phenomena are examples where surface tension reduction enables the observed effects.
49. Consider the following electromagnetic waves:
- Television broadcast
- Mobile communication
- Wi-Fi
- Visible light
Arrange the above in order of increasing frequency and select the correct sequence:
[A] 1, 2, 3, 4
[B] 2, 1, 4, 3
[C] 1, 3, 2, 4
[D] 1, 2, 3, 4
Show Answer
Correct Answer: D [1, 2, 3, 4]
Notes:
TV signals use Very High Frequency (VHF, ~50–800 MHz). Mobile communication uses higher frequencies (~800 MHz – 2 GHz). Wi-Fi uses 2.4 GHz or 5 GHz bands. Visible light lies much higher (~10¹⁴ Hz). Hence the correct ascending order is: TV < Mobile < Wi-Fi < Visible.
50. Why are electric power lines transmitted at very high voltages?
[A] Because insulation is stronger at high voltage
[B] Because transformers cannot work at low voltage
[C] Because high voltage reduces current and power loss
[D] Because high voltage increases power carried by line
Show Answer
Correct Answer: C [Because high voltage reduces current and power loss]
Notes:
Transmitting at high voltages reduces current for given power (P = VI), thus reducing resistive losses (I²R). This improves efficiency in long-distance transmission. Transformers enable voltage changes for safe distribution. Lower losses also reduce costs and heating of wires.
