Skip to content
Login Register

#radio waves

16 public questions tagged with this topic.

Applications of EM Waves in Communication and Medicine

Why are radio waves used in communication systems like cellular phones?

**Radio waves** effective for long-distance communication because low frequency waves diffract around Earth curvature and reflect from ionosphere, enabling beyond line-of-sight, used in AM (≈10⁶ Hz) ground wave, short wave sky wave. Microwaves used for satellite due to high frequency penetrates ionosphere and directional beam. Radio waves can travel long distances and penetrate obstacles like buildings due to their long wavelengths, making them ideal for communication systems. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields They travel long distances, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Applications of EM Waves in Communication and Medicine

View Details
Applications of EM Waves in Communication and Medicine

What is the typical wavelength range of radio waves used in television communication?

**X-rays and gamma rays in medicine** X-rays imaging because bone absorbs more than tissue, contrast, CT scan uses multiple X-ray projections, gamma knife uses focused gamma rays to destroy tumor with minimal surrounding damage, illustrating high-energy EM wave medical use. The document mentions that TV waves range from 54 MHz to 890 MHz . Using λ = (c/v) , this corresponds to wavelengths from about 0.34 m to 5.56 m . A simpler range based on frequency is used here. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Corresponding to 54 MHz to 890

Ref: NCERT > Physics Book > Electromagnetic Waves > Applications of EM Waves in Communication and Medicine

View Details
Applications of EM Waves in Communication and Medicine

Cellular phones use which type of electromagnetic waves for voice communication?

**X-rays and gamma rays in medicine** X-rays imaging because bone absorbs more than tissue, contrast, CT scan uses multiple X-ray projections, gamma knife uses focused gamma rays to destroy tumor with minimal surrounding damage, illustrating high-energy EM wave medical use. The document mentions that cellular phones use radio waves in the ultrahigh frequency (UHF) band for voice communication. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Radio waves, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Applications of EM Waves in Communication and Medicine

View Details
Production of EM Waves and Hertz Experiment

In the context of electromagnetic waves, what physical characteristic distinguishes radio waves from gamma rays?

**Production of EM waves** requires accelerated charge, oscillating LC circuit produces changing E and B, antenna radiates when charge accelerates, frequency determined by L and C, f=1/(2π√(LC)). Hertz used spark gap with inductor and capacitor, produced ~10⁸ Hz radio waves, detected with loop, confirmed transverse nature, reflection, refraction, polarization, speed c. Radio waves and gamma rays differ primarily in their wavelengths (or frequencies), with radio waves having much longer wavelengths (lower frequencies) than gamma rays, which have very short wavelengths. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Wavelength, illustrating EM wave transverse nature and Maxwell's displacement current concept.

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

View Details
Energy, Intensity and Momentum of EM Waves

What is the typical wavelength range of radio waves according to the document?

**Momentum of EM wave** p = U/c, U energy, radiation pressure exerts force F = I A/c, small but measurable, comet tail pushed by sunlight, solar sail concept. For E₀=45 V/m, B₀=1.5×10⁻⁷ T, intensity I =0.5×3×10⁸×8.85×10⁻¹²×45²≈2.69 W/m². The document mentions that radio waves have wavelengths greater than 0.1 m , with long radio waves extending up to 10⁶ m . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields > 0.1 m, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > Energy, Intensity and Momentum of EM Waves

View Details
Electromagnetic Spectrum - Radio Waves and Microwaves

Which type of electromagnetic waves are used in aircraft navigation radar systems?

**Hertz experiment** produced radio waves using spark gap LC oscillator, detected with loop antenna, confirming Maxwell's prediction, frequency ≈10⁸ Hz, wavelength ≈3 m, demonstrating EM waves travel at c, transverse, can be reflected, refracted, polarized. Microwaves, due to their short wavelengths, are suitable for radar systems used in aircraft navigation. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Microwaves, illustrating EM wave transverse nature and Maxwell's displacement current concept.

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

View Details
Electromagnetic Spectrum - Radio Waves and Microwaves

Why are radio waves used in GPS systems?

**Hertz experiment** produced radio waves using spark gap LC oscillator, detected with loop antenna, confirming Maxwell's prediction, frequency ≈10⁸ Hz, wavelength ≈3 m, demonstrating EM waves travel at c, transverse, can be reflected, refracted, polarized. Radio waves can travel long distances through the atmosphere and are less affected by weather, allowing satellites to transmit precise timing signals for GPS positioning. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Long-distance travel, illustrating EM wave transverse nature and Maxwell's displacement current concept.

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

View Details
EM Wave Characteristics - Transverse Nature and E/B Ratio

What type of electromagnetic waves were produced and observed by Jagdish Chandra Bose in his experiments?

**Relationship E and B** in EM wave E₀ = c B₀, B₀ = E₀/c, for vacuum. Fields sustain each other via Maxwell's equations ∇×E = -∂B/∂t, ∇×B = μ₀ ε₀ ∂E/∂t, time-varying E produces B and vice versa, self-sustaining propagation without medium, speed c. The document mentions that J.C. Bose produced and observed electromagnetic waves with wavelengths of 25 mm to 5 mm , which fall in the microwave range. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Microwaves, illustrating EM wave transverse nature and Maxwell's displacement current concept.

Ref: NCERT > Physics Book > Electromagnetic Waves > EM Wave Characteristics - Transverse Nature and E/B Ratio

View Details
Electromagnetic Spectrum - Radio Waves and Microwaves

In electromagnetic theory, what distinguishes the production mechanism of radio waves from that of visible light?

**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. Radio waves are typically produced by oscillating currents in macroscopic circuits (like antennas), while visible light arises from electron transitions between energy levels within atoms. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Different scales of oscillation, illustrating EM wave transverse nature and Maxwell's displacement current concept.

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

View Details
Electromagnetic Spectrum - Radio Waves and Microwaves

What is the approximate wavelength range of radio waves as per the document?

**Hertz experiment** produced radio waves using spark gap LC oscillator, detected with loop antenna, confirming Maxwell's prediction, frequency ≈10⁸ Hz, wavelength ≈3 m, demonstrating EM waves travel at c, transverse, can be reflected, refracted, polarized. The document states that radio waves have wavelengths greater than 0.1 m , with long radio waves up to 10⁶ m . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields > 0.1 m, illustrating EM wave transverse nature and Maxwell's displacement current concept.

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

View Details
Electromagnetic Spectrum - Radio Waves and Microwaves

What is the typical wavelength range of microwaves according to the document?

**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 microwaves have wavelengths from 0.1 m to 1 mm . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields 0.1 m to 1 mm, illustrating EM wave transverse nature and Maxwell's displacement current concept.

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

View Details
Electromagnetic Spectrum - Radio Waves and Microwaves

Radio waves are detected using which of the following?

**Microwaves** λ≈10⁻³ to 0.3 m, f≈10⁹ to 10¹² Hz, produced by klystron/magnetron, used in microwave ovens because frequency ≈2.45 GHz matches rotational resonance of water molecules, causing dielectric heating, also radar, satellite communication due to small wavelength allows directional beams. As per the document, radio waves are detected using receiver's aerials. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Receiver's aerials, illustrating EM wave transverse nature and Maxwell's displacement current concept.

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

View Details