UPSC CSE Prelims
Modern Warfare Technologies Previous Year Questions (PYQs)
Practice solved questions for Modern Warfare Technologies with detailed step-by-step solutions, key insights, and trend analysis for UPSC CSE PRELIMS.
Solved Previous Year Questions
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Which of the following statements with regard to drone swarms is/are correct ?
- They use Terahertz band of frequency to communicate with the command centre.
- Individual drones in the swarm can communicate with other drones in the swarm.
- GPS Spoofing is a commonly used technique to counter drone swarm attack.
Select the answer using the code given below :
Detailed Explanation:
Statement 1 is incorrect because drone swarms generally use conventional radio frequency (RF) bands for communication with command centres, not the Terahertz (THz) band.
Statements 2 and 3 are correct. Drones within a swarm communicate with each other to coordinate actions, and GPS spoofing is a widely used countermeasure to mislead and disrupt drone swarm navigation.
Therefore, Option B (2 and 3 only) is correct.
A drone swarm is a group of drones that work together using autonomous coordination and inter-drone communication. Swarm technology is used in surveillance, military operations, disaster management, and mapping. Countermeasures include jamming, GPS spoofing, and directed-energy systems.
Which of the following statements with regard to stealth technology is/are correct ?
- Stealth objects have a very small radar cross-section and are coated with Radar Absorbing Material.
- Stealth objects can be detected using specific frequencies.
- Stealth objects are coated with metamaterials to increase the scattering of electromagnetic radiation.
Select the answer using the code given below :
Detailed Explanation:
Statement 1 — Correct. The primary goal of stealth technology is to minimize an object's Radar Cross-Section (RCS). This is achieved through:
- Geometric shaping — to deflect radar waves away from the source
- Radar Absorbing Materials (RAM) — which absorb electromagnetic radar energy and dissipate it as heat
Statement 2 — Correct. Stealth objects are not completely invisible. RAM coatings are optimized to defeat high-frequency radars (X-band). However, low-frequency radars (VHF/UHF bands) can detect stealth objects as their longer wavelengths resonate with the aircraft's physical dimensions — though they lack resolution required for a missile lock.
Statement 3 — Incorrect. Metamaterials in stealth applications are used to decrease/eliminate radar scattering — NOT increase it. They work by:
- Perfectly absorbing electromagnetic radiation, OR
- Bending and redirecting waves around the object (electromagnetic cloaking)
Increasing scattering would make the object more visible — defeating the very purpose of stealth.
Key Trick: Statement 3 reverses the function of metamaterials — a classic UPSC trap of replacing a correct word with its opposite.
With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements:
I. All types of UAVs can do vertical landing.
II. All types of UAVs can do automated hovering.
III. All types of UAVs can use battery only as a source of power supply.
How many of the statements given above are correct?
Detailed Explanation:
The capabilities of Unmanned Aerial Vehicles (UAVs) depend on their design (fixed-wing, multirotor, hybrid, etc.). Therefore, the word "All" makes all three statements incorrect.
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Statement I is Incorrect: Not all UAVs can perform vertical landing. Fixed-wing UAVs require a runway or launcher/recovery system.
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Statement II is Incorrect: Not all UAVs can hover. Fixed-wing UAVs must keep moving forward to stay airborne.
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Statement III is Incorrect: Not all UAVs use battery power only. Many UAVs use fuel engines, hybrid systems, or even solar power.
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Therefore, none of the statements are correct, making Option D the correct answer.
Statement-wise Analysis
| Statement | Status | Explanation |
|---|---|---|
| I. All UAVs can do vertical landing | ❌ Incorrect | Only VTOL and multirotor UAVs can land vertically. |
| II. All UAVs can do automated hovering | ❌ Incorrect | Fixed-wing UAVs cannot hover. |
| III. All UAVs use battery only | ❌ Incorrect | UAVs may use fuel, hybrid, solar, or battery power. |
Types of UAVs
| Type | Hovering | Vertical Take-off/Landing | Power Source |
|---|---|---|---|
| Fixed-Wing | ❌ No | ❌ No | Fuel, Battery, Hybrid |
| Multirotor | ✅ Yes | ✅ Yes | Mostly Battery |
| VTOL Hybrid | ✅ Yes | ✅ Yes | Battery, Fuel, Hybrid |
Important Facts
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Fixed-wing UAVs are preferred for long-range surveillance and mapping.
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Multirotor drones are ideal for photography, monitoring, and inspection.
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Hybrid UAVs combine the advantages of fixed-wing and multirotor systems.
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Modern UAVs can be powered by batteries, internal combustion engines, hydrogen fuel cells, or solar energy.
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