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
v = 2.21 × 10⁸ m/s

Light travels at 2.21 × 10⁸ m/s in a transparent material. Find its refractive index n.

v = 2.21 × 10⁸ m/sc = 3.00 × 10⁸ m/s
n =
2.Easy
PI = 3 × 10⁻⁴ W/m²

The sound intensity near a lawn mower is 3 × 10⁻⁴ W/m². Find the sound intensity level β in decibels.

I = 3 × 10⁻⁴ W/m²I0 = 10⁻¹² W/m²
β = dB
3.Medium
70 dB?10 m80 m

A small source sends sound equally in all directions. The level is 70 dB at 10 m from it. Find the level β2 at 80 m, ignoring absorption and reflections.

β1 = 70 dBr1 = 10 mr2 = 80 m
β2 = dB
4.Medium
FFdo​ = 25 cmf = 10 cm

An object stands 25 cm in front of a thin converging lens with a focal length of 10 cm. Find the magnification m (negative for an inverted image).

do = 25 cmf = 10 cm
m =
5.Hard
λ = 405 nmθ1​ = ?

Light of wavelength 405 nm falls at right angles on a grating with 800 lines per millimetre. Find the angle θ1 of the order-1 maximum.

N = 800 mm⁻¹λ = 405 nmm = 1
θ1 = °
6.Hard
λ = 532 nmθ1​ = ?

Light of wavelength 532 nm falls at right angles on a grating with 800 lines per millimetre. Find the angle θ1 of the order-1 maximum.

N = 800 mm⁻¹λ = 532 nmm = 1
θ1 = °

Answer key

  1. 1. n = 1.357
  2. 2. β = 84.77 dB
  3. 3. β2 = 51.94 dB
  4. 4. m = −0.6667
  5. 5. θ1 = 18.91 °
  6. 6. θ1 = 25.19 °

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