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 = ?v = 3.00 × 10⁸ m/sf = 107.9 MHz

A radio wave has a frequency of 107.9 MHz and travels at 3.00 × 10⁸ m/s. Find its wavelength λ.

f = 107.9 MHzv = 3.00 × 10⁸ m/s
λ = m
2.Easy
λ = 4 mv = 2 m/sf = ?

A water wave travels at 2 m/s with a wavelength of 4 m. Find its frequency f.

λ = 4 mv = 2 m/s
f = Hz
3.Medium
L = 1.5 mn = 3

A pipe closed at one end is 1.5 m long. The speed of sound is 343 m/s. Find the frequency f3 of its harmonic number 3.

v = 343 m/sn = 3L = 1.5 m
f3 = Hz
4.Medium
FFdo​ = 15 cmf = 5 cm

An object stands 15 cm in front of a thin converging lens with a focal length of 5 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 = 15 cmf = 5 cm
di = cm
5.Hard
θn1​ = 1.46n2​ = 1.45n0​ = 1.00

An optical fibre has a core with n₁ = 1.46 and a cladding with n₂ = 1.45. Find its numerical aperture NA.

n1 = 1.46n2 = 1.45
NA =
6.Hard
θn1​ = 1.55n2​ = 1.52n0​ = 1.00

An optical fibre has a core with n₁ = 1.55 and a cladding with n₂ = 1.52. Find its numerical aperture NA.

n1 = 1.55n2 = 1.52
NA =

Answer key

  1. 1. λ = 2.78 m
  2. 2. f = 0.5 Hz
  3. 3. f3 = 171.5 Hz
  4. 4. di = 7.5 cm
  5. 5. NA = 0.1706
  6. 6. NA = 0.3035

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