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#theory

5 public questions tagged with this topic.

Electromagnetic Spectrum - Radio Waves and Microwaves

What type of electromagnetic waves did Maxwell predict before their experimental discovery?

**Radio waves** λ≈10⁻¹ to 10⁴ m, f≈10⁴ to 10⁹ Hz, produced by rapid acceleration/deceleration of electrons in aerials/antenna, used for long-distance communication because low frequency diffracts around obstacles and reflects from ionosphere, enabling ground wave and sky wave propagation, effective for broadcasting. The document mentions that Maxwell predicted the existence of electromagnetic waves, which were later confirmed to include light, radio waves, and others, but initially, they were general EM waves. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, eval

Ref: NCERT > Physics Book > Electromagnetic Waves > Electromagnetic Spectrum - Radio Waves and Microwaves

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Solenoid, Toroid and Ampere's Law

Why is the magnetic field outside a long solenoid considered negligible?

**Solenoid field** inside long solenoid is B = μ₀ n I, n = N/L turns per meter (m⁻¹), uniform and parallel to axis, outside negligible for long solenoid because fields from opposite sides cancel. For n = 1200 m⁻¹, I = 1 A, B = 4π×10⁻⁷×1200 = 1.51×10⁻³ T = 1.51 mT. In a long solenoid, the magnetic field lines are concentrated inside, and outside, the fields from opposite sides of the coils cancel each other, making the external field nearly zero. Using F = q v B sinθ, F = I l B sinθ, B = μ₀ I/(2π r), B = μ₀ N I/(2R)

Ref: NCERT > Physics Book > Moving Charge and Magnetism > Solenoid, Toroid and Ampere's Law

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ORIGIN OF LIFE

Creationism is rejected because:

No explanation of adaptation reflects key principle in quiz on section b pyqs- origin of life, where evolutionary mechanisms shape genetic variation and adaptation. In this context, No explanation of adaptation aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why No explanation of adaptation fits helps integrate natural selection, drift and species concepts essential for NEET, CSIR-NET and GATE examinations. Thi

Ref: Miller & Lazcano, J Mol Evol, Prebiotic Chemistry and RNA World.

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