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Wave Equation and Displacement Relation

This category covers the fundamental relationship between wave equations and displacement in physics. It includes concepts, derivations, and example problems that illustrate how displacement varies with time and position in wave motion.

30 questions

A transverse wave on a string has a speed of 24 m/s and a period of 0.02 s. What is its wavelength?

**Displacement relation** encodes λ = 2π/k and f = ω/2π. Comparing given equation y = a sin(kx - ωt) with standard form yields k and ω, hence λ = 2π/k and v = ω/k, essential for identifying propagation characteristics and phase. Frequency: v = (1/T) = (1/0.02) = 50 Hz . Wavelength: λ = (v/v) = (24/50) = 0.48 m . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 0.48 m, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A wave on a string has an amplitude of 0.02 m and a period of 0.01 s. What is the maximum transverse speed of a particle

**Wave equation** y(x,t) = A sin(kx - ωt + φ) describes displacement of progressive harmonic wave, where k = 2π/λ wave number (rad/m), ω = 2πf angular frequency (rad/s), v = ω/k wave speed (m/s). Sign of ωt indicates direction, amplitude A is maximum displacement. ω = (2π/T) = (2π/0.01) = 200π rad/s . Max speed: vₘₐₓ = a ω = 0.02 × 200π ≈ 12.57 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 12.6 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A transverse wave on a string has a speed of 30 m/s and a wavelength of 1.5 m. What is the time period of the wave?

**Displacement relation** encodes λ = 2π/k and f = ω/2π. Comparing given equation y = a sin(kx - ωt) with standard form yields k and ω, hence λ = 2π/k and v = ω/k, essential for identifying propagation characteristics and phase. Speed: v = v λ , v = (v/λ) = (30/1.5) = 20 Hz . Time period: T = (1/v) = (1/20) = 0.05 s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 0.05 s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A longitudinal wave travels in a medium with bulk modulus 1.8 × 10⁹ Pa and density 900 kg/m³. What is its speed?

**Wave equation** y(x,t) = A sin(kx - ωt + φ) describes displacement of progressive harmonic wave, where k = 2π/λ wave number (rad/m), ω = 2πf angular frequency (rad/s), v = ω/k wave speed (m/s). Sign of ωt indicates direction, amplitude A is maximum displacement. Speed: v = √((B/rho)) = √((1.8 × 10⁹/900)) = √(2 × 10⁶) ≈ 1414 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 1400 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A wave on a string has an amplitude of 0.04 m and a period of 0.025 s. What is the maximum transverse speed of a particl

**Sinusoidal wave form** represents harmonic wave where each particle executes SHM. Coefficients of x and t give spatial and temporal periodicities, allowing wavelength and period extraction, basis for wave analysis in NCERT. ω = (2π/T) = (2π/0.025) = 80π rad/s . Max speed: vₘₐₓ = a ω = 0.04 × 80π ≈ 10.05 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 10 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A wave is described by \( y(x, t) = 0.05 \sin (45x - 90t) \), where \( x \) and \( y \) are in meters and \( t \) in sec

**Sinusoidal wave form** represents harmonic wave where each particle executes SHM. Coefficients of x and t give spatial and temporal periodicities, allowing wavelength and period extraction, basis for wave analysis in NCERT. Compare with y = a sin (kx - ω t) , k = 45 rad/m , ω = 90 rad/s . Speed: v = (ω/k) = (90/45) = 2 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 2 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

Which wave type is most likely to propagate fastest in a solid medium?

**Wave equation** y(x,t) = A sin(kx - ωt + φ) describes displacement of progressive harmonic wave, where k = 2π/λ wave number (rad/m), ω = 2πf angular frequency (rad/s), v = ω/k wave speed (m/s). Sign of ωt indicates direction, amplitude A is maximum displacement. In solids, longitudinal waves (P-waves) travel faster than transverse waves (S-waves) because the bulk modulus plus shear modulus exceeds the shear modulus alone, increasing speed. Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields Longitudinal, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A longitudinal wave in a medium has a speed of 1550 m/s and a density of 1200 kg/m³. What is the bulk modulus of the med

**Sinusoidal wave form** represents harmonic wave where each particle executes SHM. Coefficients of x and t give spatial and temporal periodicities, allowing wavelength and period extraction, basis for wave analysis in NCERT. Speed: v = √((B/rho)) . 1550 = √((B/1200)) ⇒ 1550² = (B/1200) . B = 1550² × 1200 = 2.88 × 10⁹ Pa . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 2.88 × 10⁹ Pa, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A wave is described by \( y(x, t) = 0.06 \sin (30x - 90t) \), where \( x \) and \( y \) are in meters and \( t \) in sec

**Sinusoidal wave form** represents harmonic wave where each particle executes SHM. Coefficients of x and t give spatial and temporal periodicities, allowing wavelength and period extraction, basis for wave analysis in NCERT. Compare with y = a sin (kx - ω t) . k = 30 rad/m , ω = 90 rad/s . Speed: v = (ω/k) = (90/30) = 3 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 3 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A longitudinal wave in a medium has a speed of 1700 m/s and a bulk modulus of 2.89 × 10⁹ Pa. What is the density of the

**Sinusoidal wave form** represents harmonic wave where each particle executes SHM. Coefficients of x and t give spatial and temporal periodicities, allowing wavelength and period extraction, basis for wave analysis in NCERT. Speed: v = √((B/rho)) . 1700 = √((2.89 × 10⁹/rho)) ⇒ 1700² = (2.89 × 10⁹/rho) . rho = (2.89 × 10⁹/1700²) = (2.89 × 10⁹/2.89 × 10⁶) = 1000 kg/m³ . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 1000 kg/m³, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

What happens to a transverse wave when it reflects off a fixed end of a string?

**Displacement relation** encodes λ = 2π/k and f = ω/2π. Comparing given equation y = a sin(kx - ωt) with standard form yields k and ω, hence λ = 2π/k and v = ω/k, essential for identifying propagation characteristics and phase. At a fixed end, the displacement must be zero, requiring the reflected wave to be out of phase by π radians (inverted) to cancel the incident wave at the boundary. Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields It reflects with a phase change of π radians, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A wave is described by \( y(x, t) = 0.02 \sin (25x - 75t) \), where \( x \) and \( y \) are in meters and \( t \) in sec

**Displacement relation** encodes λ = 2π/k and f = ω/2π. Comparing given equation y = a sin(kx - ωt) with standard form yields k and ω, hence λ = 2π/k and v = ω/k, essential for identifying propagation characteristics and phase. Compare with y = a sin (kx - ω t) , ω = 75 rad/s . Period: T = (2π/ω) = (2π/75) ≈ 0.0838 s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 0.08 s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation