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 = 50 dB

The sound intensity level at a point is 50 dB. Find the sound intensity I.

β = 50 dBI0 = 10⁻¹² W/m²
I = µW/m²
2.Easy
λ = ?v = 1480 m/sf = 100 Hz

A sound wave in water has a frequency of 100 Hz and travels at 1480 m/s. Find its wavelength λ.

f = 100 Hzv = 1480 m/s
λ = m
3.Medium
L = 0.65 mn = 7

A pipe closed at one end is 0.65 m long. The speed of sound is 343 m/s. Find the frequency f7 of its harmonic number 7.

v = 343 m/sn = 7L = 0.65 m
f7 = Hz
4.Medium
θc = ?90°ethanol, n1​ = 1.36air, n2​ = 1.00

Light travels in ethanol (n = 1.36) towards a flat boundary with air (n = 1.00). Find the critical angle θc beyond which it is totally reflected.

n1 = 1.36n2 = 1.00
θc = °
5.Hard
λ = 589 nmθ

A diffraction grating has 400 lines per millimetre. Light of wavelength 589 nm falls on it at right angles. What is the highest order mmax of bright maximum that can be seen?

N = 400 mm⁻¹λ = 589 nm
mmax =
6.Hard
λ = 633 nmθ1​ = ?

Light of wavelength 633 nm falls at right angles on a grating with 600 lines per millimetre. Find the angle θ1 of the order-1 maximum.

N = 600 mm⁻¹λ = 633 nmm = 1
θ1 = °

Answer key

  1. 1. I = 0.1 µW/m²
  2. 2. λ = 14.8 m
  3. 3. f7 = 923.5 Hz
  4. 4. θc = 47.33 °
  5. 5. mmax = 4
  6. 6. θ1 = 22.32 °

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