#ultraviolet

Production of EM Waves and Hertz Experiment

What is the wavelength range of ultraviolet rays as per the electromagnetic spectrum?

**Hertz experiment** used induction coil connected to two rods with gap, spark produced oscillating charge, emitted EM wave, received by loop with gap sparking when E induced, measured wavelength by standing wave, demonstrated EM wave properties, validating Maxwell. The document states that ultraviolet rays range from about 400 nm to 0.6 nm . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields 400 nm to 0.6 nm, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Production of EM Waves and Hertz Experiment

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Environmental Effects - Ozone, Greenhouse and Safety

The ozone layer protects the Earth by absorbing which type of electromagnetic waves?

**Greenhouse effect** IR absorbed by CO₂, H₂O, CH₄, warming Earth, excessive greenhouse due to fossil fuel burning raises temperature, EM waves role: Sun visible reaches surface, Earth emits IR trapped, altering energy balance, safety concern for climate change. The document mentions that the ozone layer absorbs most ultraviolet (UV) radiation, protecting life on Earth. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Ultraviolet rays, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Environmental Effects - Ozone, Greenhouse and Safety

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Environmental Effects - Ozone, Greenhouse and Safety

What is the primary source of ultraviolet radiation mentioned in the document?

**Ozone layer depletion** environmental concern related to increased UV-B reaching surface, causing skin cancer, cataracts, damage to crops and marine life, due to CFCs releasing Cl that catalytically destroys O₃, O₃ absorbs UV 200-320 nm, depletion increases UV transmission. The document states that the sun is an important source of ultraviolet light, though much of it is absorbed by the ozone layer. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields The sun, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Environmental Effects - Ozone, Greenhouse and Safety

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Environmental Effects - Ozone, Greenhouse and Safety

In the electromagnetic spectrum, what characteristic of UV rays makes them harmful to human tissue?

**Ozone layer depletion** environmental concern related to increased UV-B reaching surface, causing skin cancer, cataracts, damage to crops and marine life, due to CFCs releasing Cl that catalytically destroys O₃, O₃ absorbs UV 200-320 nm, depletion increases UV transmission. UV rays have higher energy due to their shorter wavelengths (higher frequencies), which can damage living tissues by breaking molecular bonds, leading to effects like skin cancer. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Their high energy, illustrating EM wave trans

Ref: NCERT > Physics Book > Electromagnetic Waves > Environmental Effects - Ozone, Greenhouse and Safety

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Ultraviolet, X-rays, Gamma Rays and Their Properties

Why are ultraviolet lamps used in water purifiers?

**X-rays in medicine** treat certain cancers because high-energy photons ionize and damage DNA of malignant cells, also imaging because bones absorb more than tissue, contrast. Gamma rays from Co-60 used for radiotherapy, energy ≈1.17 and 1.33 MeV, highly penetrating. UV lamps are used to kill germs in water purifiers due to their ability to damage living organisms, as mentioned in the document. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields To kill germs, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Ultraviolet, X-rays, Gamma Rays and Their Properties

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Ultraviolet, X-rays, Gamma Rays and Their Properties

Why are UV lamps used in LASIK eye surgery?

**X-rays in medicine** treat certain cancers because high-energy photons ionize and damage DNA of malignant cells, also imaging because bones absorb more than tissue, contrast. Gamma rays from Co-60 used for radiotherapy, energy ≈1.17 and 1.33 MeV, highly penetrating. The document mentions that due to their shorter wavelengths, UV rays can be focused into narrow beams, making them suitable for high-precision applications like LASIK eye surgery. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields They can be focused into narrow beams, illustrating E

Ref: NCERT > Physics Book > Electromagnetic Waves > Ultraviolet, X-rays, Gamma Rays and Their Properties

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PHYSICS

Why are ultraviolet lamps used in water purifiers?

UV lamps are used to kill germs in water purifiers due to their ability to damage living organisms, as mentioned in the document. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Physics Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII, continuing as per NCERT advisory for 2026-27),Topic: Fundamental laws, definitions and applications as per latest NCERT. The section explains governing laws, formulas like μ₀ = 4π.

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