Waves, sound & optics worksheet with answers

Free printable Waves, sound & optics worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
Pβ = 40 dB

The sound intensity level at a point is 40 dB. Find the sound intensity I.

β = 40 dBI0 = 10⁻¹² W/m²
I = µW/m²
2.Easy
PI = 3 × 10⁻² W/m²

The sound intensity near a rock concert is 3 × 10⁻² W/m². Find the sound intensity level β in decibels.

I = 3 × 10⁻² W/m²I0 = 10⁻¹² W/m²
β = dB
3.Medium
L = ?n = 1

A pipe closed at one end must have its fundamental (first harmonic) at 57 Hz. The speed of sound is 343 m/s. Find the length L of the pipe.

v = 343 m/sn = 1f1 = 57 Hz
L = m
4.Medium
SO20 m/sf = 600 Hz

An observer moves at 20 m/s away from a stationary source of 600 Hz. The speed of sound is 343 m/s. Find the frequency f′ that the observer hears.

f = 600 Hzv = 343 m/svo = 20 m/s
f′ = Hz
5.Hard
Fdo​ = 40 cmR = 24 cm

An object is 40 cm in front of a convex mirror with a radius of curvature of 24 cm. Find the image distance di, positive for an image in front of the mirror (real) and negative for one behind it (virtual).

do = 40 cmR = 24 cm
di = cm
6.Hard
λ = 656 nmθ3​ = ?

Light of wavelength 656 nm falls at right angles on a grating with 300 lines per millimetre. Find the angle θ3 of the order-3 maximum.

N = 300 mm⁻¹λ = 656 nmm = 3
θ3 = °

Answer key

  1. 1. I = 0.01 µW/m²
  2. 2. β = 104.8 dB
  3. 3. L = 1.504 m
  4. 4. f′ = 565 Hz
  5. 5. di = −9.231 cm
  6. 6. θ3 = 36.19 °

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