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 = ?

Light with a wavelength of 633 nm in vacuum enters ethanol (n = 1.36). Find its wavelength λ inside the material.

n = 1.36λ0 = 633 nm
λ = nm
2.Easy
L = 0.6 m

A string of length 0.6 m and mass 4 g is stretched with a tension of 100 N. Find the speed v of transverse waves on it.

L = 0.6 mm = 4 gT = 100 N
v = m/s
3.Medium
Pβ = ?r = 10 m

A small loudspeaker radiates 0.1 W of sound power equally in all directions. Find the sound intensity level β at 10 m.

P = 0.1 Wr = 10 mI0 = 10⁻¹² W/m²
β = dB
4.Medium
FFdo​ = 12 cmf = −5 cm

An object stands 12 cm in front of a thin diverging 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 = 12 cmf = −5 cm
di = cm
5.Hard
λ = ?d = 0.25 mmL = 2 m16 mm

Two slits 0.25 mm apart are lit with monochromatic light. On a screen 2 m away, bright fringe number 4 lies 16 mm from the central fringe. Find the wavelength λ.

d = 0.25 mmL = 2 my4 = 16 mmm = 4
λ = nm
6.Hard
Fdo​ = 5 cmR = 30 cm

An object is 5 cm in front of a convex mirror with a radius of curvature of 30 cm. Find the magnification m (negative for an inverted image).

do = 5 cmR = 30 cm
m =

Answer key

  1. 1. λ = 465.4 nm
  2. 2. v = 122.5 m/s
  3. 3. β = 79.01 dB
  4. 4. di = −3.529 cm
  5. 5. λ = 500 nm
  6. 6. m = 0.75

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