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
L = 1.2 m

A string of length 1.2 m and mass 10 g carries transverse waves at 173.2 m/s. Find the tension T in the string.

L = 1.2 mm = 10 gv = 173.2 m/s
T = N
2.Easy
λ = ?v = 1.5 m/sf = 2 Hz

A water wave has a frequency of 2 Hz and travels at 1.5 m/s. Find its wavelength λ.

f = 2 Hzv = 1.5 m/s
λ = m
3.Medium
P10 × 70 dB

One machine gives a sound level of 70 dB at a certain point. Find the level β at that point when 10 identical machines run at the same time (incoherent sources).

β1 = 70 dBn = 10
β = dB
4.Medium
θc = ?90°crown glass, n1​ = 1.50air, n2​ = 1.00

Light travels in crown glass (n = 1.50) towards a flat boundary with air (n = 1.00). Find the critical angle θc beyond which it is totally reflected.

n1 = 1.50n2 = 1.00
θc = °
5.Hard
Fdo​ = 30 cmR = 10 cm

An object is 30 cm in front of a concave mirror with a radius of curvature of 10 cm. Find the magnification m (negative for an inverted image).

do = 30 cmR = 10 cm
m =
6.Hard
f1​ = 8 cmf2​ = 12 cm30 cm15 cm

Two thin lenses share an axis, 15 cm apart: lens 1 with f₁ = 8 cm and lens 2 with f₂ = 12 cm. An object stands 30 cm in front of lens 1. Find the position di2 of the final image measured from lens 2 (positive beyond lens 2, real-is-positive convention).

f1 = 8 cmf2 = 12 cms = 15 cmdo = 30 cm
di2 = cm

Answer key

  1. 1. T = 250 N
  2. 2. λ = 0.75 m
  3. 3. β = 80 dB
  4. 4. θc = 41.81 °
  5. 5. m = −0.2
  6. 6. di2 = −6.207 cm

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