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 = 85 dB

The sound intensity level at a point is 85 dB. Find the sound intensity I.

β = 85 dBI0 = 10⁻¹² W/m²
I = µW/m²
2.Easy
v = ?

Find the speed v of light in water, which has a refractive index of 1.33.

n = 1.33c = 3.00 × 10⁸ m/s
v = m/s
3.Medium
FF1 cmdo​ = 20 cmf = −25 cm

An object 1 cm tall stands 20 cm in front of a thin diverging lens with a focal length of 25 cm. Find the image height hi (negative for an inverted image).

ho = 1 cmdo = 20 cmf = −25 cm
hi = cm
4.Medium
L = ?n = 5

A pipe open at both ends must have its harmonic number 5 at 1072 Hz. The speed of sound is 343 m/s. Find the length L of the pipe.

v = 343 m/sn = 5f5 = 1072 Hz
L = m
5.Hard
λ = 656 nmθ

A diffraction grating has 1200 lines per millimetre. Light of wavelength 656 nm falls on it at right angles. What is the highest order mmax of bright maximum that can be seen?

N = 1200 mm⁻¹λ = 656 nm
mmax =
6.Hard
λ = 650 nmd = 0.3 mmL = 2 my = ?

Light of wavelength 650 nm falls on two slits 0.3 mm apart. The screen is 2 m away. Find the distance y4 from the central bright fringe to bright fringe number 4.

λ = 650 nmd = 0.3 mmL = 2 mm = 4
y4 = mm

Answer key

  1. 1. I = 316.2 µW/m²
  2. 2. v = 2.256 × 10⁸ m/s
  3. 3. hi = 0.5556 cm
  4. 4. L = 0.7999 m
  5. 5. mmax = 1
  6. 6. y4 = 17.33 mm

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