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
λ = 3.141 mv = 3.00 × 10⁸ m/sf = ?

A radio wave travels at 3.00 × 10⁸ m/s with a wavelength of 3.141 m. Find its frequency f.

λ = 3.141 mv = 3.00 × 10⁸ m/s
f = MHz
2.Easy
v = ?

Find the speed v of light in ethanol, which has a refractive index of 1.36.

n = 1.36c = 3.00 × 10⁸ m/s
v = m/s
3.Medium
L = 0.8 mn = 4

A pipe open at both ends is 0.8 m long. The speed of sound is 343 m/s. Find the frequency f4 of its harmonic number 4.

v = 343 m/sn = 4L = 0.8 m
f4 = Hz
4.Medium
FFdo​ = 60 cmf = 10 cm

An object stands 60 cm in front of a thin converging lens with a focal length of 10 cm. Find the image distance di. Use the sign convention 1/f = 1/do + 1/di (f < 0 for a diverging lens, di < 0 for a virtual image).

do = 60 cmf = 10 cm
di = cm
5.Hard
λ = 600 nma = 0.12 mmL = 2 m

Light of wavelength 600 nm passes through a single slit 0.12 mm wide. Find the width w of the central bright maximum on a screen 2 m away (between the first dark fringes on either side).

λ = 600 nma = 0.12 mmL = 2 m
w = mm
6.Hard
θa​ = ?n1​ = 1.48n2​ = 1.47n0​ = 1.00

An optical fibre has a core with n₁ = 1.48 and a cladding with n₂ = 1.47. Find the largest angle θa to the fibre axis at which light from air can enter the end of the fibre and still be guided by total internal reflection.

n1 = 1.48n2 = 1.47n0 = 1.00
θa = °

Answer key

  1. 1. f = 95.5 MHz
  2. 2. v = 2.206 × 10⁸ m/s
  3. 3. f4 = 857.5 Hz
  4. 4. di = 12 cm
  5. 5. w = 20 mm
  6. 6. θa = 9.89 °

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