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#satellites

3 public questions tagged with this topic.

Infrared, Visible Light and Applications

Why are infrared detectors used in Earth satellites?

**IR effectiveness in remote sensing** because IR scattered less than visible by atmosphere, can detect heat signatures, used in satellite imaging for vegetation, moisture, military night vision, illustrating application based on thermal emission and low scattering. Infrared detectors are used for military purposes and to observe crop growth, as stated in the document. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields For military purposes and crop observation, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Infrared, Visible Light and Applications

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Potential Energy of Mass Systems

How much energy is required to move a 200kg satellite from 6RE to 12RE from Earth’s center? (ME\=6×1024kg,RE\=6.4×106m,G

ΔE = −GMEm(1r2−1r1). r1 = 3.84×107m, r2 = 7.68×107m. ΔE = −6.67×10−11×6×1024×200(17.68×107−13.84×107). ΔE = −8.004×1016(−1.302×10−8)≈1.04×109J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.0 × 10⁹ J. This satisfies dimensional consistency and physical conditions given, so option A is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

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