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Wave Speed, Energy and Power

This category covers the basic concepts of wave speed, the energy carried by waves, and the power associated with wave motion. It explains how these quantities are defined, calculated, and applied in typical physics scenarios.

30 questions

A transverse wave travels on a string with a tension of 200 N and linear mass density of 0.025 kg/m. What is the wavelen

**Energy transport** in waves scales with amplitude squared A² and frequency squared ω². Wave speed determines propagation rate, and understanding T and μ allows quantitative prediction of v and associated frequencies. Speed: v = √((T/μ)) = √((200/0.025)) = √(8000) ≈ 89.4 m/s . Wavelength: λ = (v/v) = (89.4/40) ≈ 2.24 m . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 2.24 m, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A string of length 1.8 m and mass 0.045 kg has a fundamental frequency of 40 Hz. What is the tension in the string?

**Transverse wave velocity** depends on medium not frequency alone. For string under tension, v ∝ √(T/μ), calculation requires μ from mass and length, then square root evaluation, giving v in m/s, then f = v/λ for given wavelength. μ = (0.045/1.8) = 0.025 kg/m . v₁ = (v/2L) ⇒ 40 = (v/2 × 1.8) ⇒ v = 40 × 3.6 = 144 m/s . v = √((T/μ)) ⇒ 144 = √((T/0.025)) ⇒ 144² = (T/0.025) . T = 20736 × 0.025 = 518.4 N . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 518 N, illustrating

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A string of length 4 m and mass 0.016 kg is under a tension of 64 N. What is the speed of a transverse wave on the strin

**Energy transport** in waves scales with amplitude squared A² and frequency squared ω². Wave speed determines propagation rate, and understanding T and μ allows quantitative prediction of v and associated frequencies. Linear mass density: μ = (0.016/4) = 0.004 kg/m . Speed: v = √((T/μ)) = √((64/0.004)) = √(16000) ≈ 126.5 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 126 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A string of length 5 m and mass 0.05 kg is under a tension of 80 N. How long does a transverse pulse take to travel its

**Wave speed on string** is v = √(T/μ), T tension (N), μ = m/L linear mass density (kg/m). Higher T increases restoring force raising speed, heavier μ lowers speed. Frequency follows f = v/λ, linking mechanical properties to wave dynamics and harmonic series. Linear mass density: μ = (0.05/5) = 0.01 kg/m . Speed: v = √((T/μ)) = √((80/0.01)) = √(8000) ≈ 89.44 m/s . Time: t = (length/v) = (5/89.44) ≈ 0.056 s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 0.056 s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A string of length 1.8 m and mass 0.036 kg has a fundamental frequency of 50 Hz. What is the tension in the string?

**Transverse wave velocity** depends on medium not frequency alone. For string under tension, v ∝ √(T/μ), calculation requires μ from mass and length, then square root evaluation, giving v in m/s, then f = v/λ for given wavelength. μ = (0.036/1.8) = 0.02 kg/m . v₁ = (v/2L) ⇒ 50 = (v/2 × 1.8) ⇒ v = 50 × 3.6 = 180 m/s . v = √((T/μ)) ⇒ 180 = √((T/0.02)) ⇒ 180² = (T/0.02) . T = 32400 × 0.02 = 648 N . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 648 N, illustrating

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A transverse wave on a string has a tension of 120 N and a linear mass density of 0.015 kg/m. What is the wavelength if

**Wave speed on string** is v = √(T/μ), T tension (N), μ = m/L linear mass density (kg/m). Higher T increases restoring force raising speed, heavier μ lowers speed. Frequency follows f = v/λ, linking mechanical properties to wave dynamics and harmonic series. Speed: v = √((T/μ)) = √((120/0.015)) = √(8000) ≈ 89.44 m/s . Wavelength: λ = (v/v) = (89.44/50) ≈ 1.79 m . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 1.8 m, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A transverse wave travels on a string with tension 400 N and linear mass density 0.1 kg/m. What is the speed of the wave

**Energy transport** in waves scales with amplitude squared A² and frequency squared ω². Wave speed determines propagation rate, and understanding T and μ allows quantitative prediction of v and associated frequencies. Speed: v = √((T/μ)) = √((400/0.1)) = √(4000) ≈ 63.25 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 63.2 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries. This aligns with NCERT Class 11 treatment, emphasizing conservation, symmetry and dimensional consistency useful for CBSE, NEET and CUET.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

Which property of a sound wave is most directly responsible for its loudness?

**Transverse wave velocity** depends on medium not frequency alone. For string under tension, v ∝ √(T/μ), calculation requires μ from mass and length, then square root evaluation, giving v in m/s, then f = v/λ for given wavelength. Loudness is primarily determined by the amplitude of a sound wave, as it relates to the energy carried and perceived intensity, while frequency affects pitch. Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields Amplitude, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A string of length 2.8 m and mass 0.07 kg has a fundamental frequency of 35 Hz. What is the tension in the string?

**Wave speed on string** is v = √(T/μ), T tension (N), μ = m/L linear mass density (kg/m). Higher T increases restoring force raising speed, heavier μ lowers speed. Frequency follows f = v/λ, linking mechanical properties to wave dynamics and harmonic series. μ = (0.07/2.8) = 0.025 kg/m . v₁ = (v/2L) ⇒ 35 = (v/2 × 2.8) ⇒ v = 35 × 5.6 = 196 m/s . v = √((T/μ)) ⇒ 196 = √((T/0.025)) ⇒ 196² = (T/0.025) . T = 38416 × 0.025 = 960.4 N . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable,

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A string of length 2.5 m and mass 0.05 kg has a wave speed of 100 m/s. What is the tension in the string?

**Energy transport** in waves scales with amplitude squared A² and frequency squared ω². Wave speed determines propagation rate, and understanding T and μ allows quantitative prediction of v and associated frequencies. μ = (0.05/2.5) = 0.02 kg/m . v = √((T/μ)) ⇒ 100 = √((T/0.02)) ⇒ 100² = (T/0.02) . T = 10000 × 0.02 = 200 N . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 200 N, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A transverse wave on a string has a tension of 200 N and a linear mass density of 0.04 kg/m. What is the wavelength if t

**Energy transport** in waves scales with amplitude squared A² and frequency squared ω². Wave speed determines propagation rate, and understanding T and μ allows quantitative prediction of v and associated frequencies. Speed: v = √((T/μ)) = √((200/0.04)) = √(5000) ≈ 70.71 m/s . Wavelength: λ = (v/v) = (70.71/25) ≈ 2.83 m . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 2.83 m, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power

A transverse wave on a string has a tension of 90 N and a linear mass density of 0.01 kg/m. What is the frequency if the

**Transverse wave velocity** depends on medium not frequency alone. For string under tension, v ∝ √(T/μ), calculation requires μ from mass and length, then square root evaluation, giving v in m/s, then f = v/λ for given wavelength. Speed: v = √((T/μ)) = √((90/0.01)) = √(9000) ≈ 94.87 m/s . Frequency: v = (v/λ) = (94.87/1.5) ≈ 63.25 Hz . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 63 Hz, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Speed, Energy and Power