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
PI = 8 × 10⁻⁴ W/m²

The sound intensity near a lawn mower is 8 × 10⁻⁴ W/m². Find the sound intensity level β in decibels.

I = 8 × 10⁻⁴ W/m²I0 = 10⁻¹² W/m²
β = dB
2.Easy
L = 2.5 m

A string of length 2.5 m and mass 12 g carries transverse waves at 228.2 m/s. Find the tension T in the string.

L = 2.5 mm = 12 gv = 228.2 m/s
T = N
3.Medium
L = ?n = 1

A pipe closed at one end must have its fundamental (first harmonic) at 214 Hz. The speed of sound is 343 m/s. Find the length L of the pipe.

v = 343 m/sn = 1f1 = 214 Hz
L = m
4.Medium
S10 m/sOf = 1200 Hz

A source of 1200 Hz moves at 10 m/s away from a stationary observer. The speed of sound is 343 m/s. Find the frequency f′ that the observer hears.

f = 1200 Hzv = 343 m/svs = 10 m/s
f′ = Hz
5.Hard
λ = 532 nmd = 0.3 mmL = 2 my = ?

Light of wavelength 532 nm falls on two slits 0.3 mm apart. The screen is 2 m away. Find the distance y2 from the central bright fringe to bright fringe number 2.

λ = 532 nmd = 0.3 mmL = 2 mm = 2
y2 = mm
6.Hard
λ = 532 nmθ

A diffraction grating has 400 lines per millimetre. Light of wavelength 532 nm falls on it at right angles. What is the highest order mmax of bright maximum that can be seen?

N = 400 mm⁻¹λ = 532 nm
mmax =

Answer key

  1. 1. β = 89.03 dB
  2. 2. T = 250 N
  3. 3. L = 0.4007 m
  4. 4. f′ = 1166 Hz
  5. 5. y2 = 7.093 mm
  6. 6. mmax = 4

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