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 = 0.68 mv = 340 m/sf = ?

A sound wave in air travels at 340 m/s with a wavelength of 0.68 m. Find its frequency f.

λ = 0.68 mv = 340 m/s
f = Hz
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
θc = ?90°diamond, n1​ = 2.42ethanol, n2​ = 1.36

Light travels in diamond (n = 2.42) towards a flat boundary with ethanol (n = 1.36). Find the critical angle θc beyond which it is totally reflected.

n1 = 2.42n2 = 1.36
θc = °
4.Medium
FFdo​ = 20 cmf = −25 cm

An object stands 20 cm in front of a thin diverging lens with a focal length of 25 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 = 20 cmf = −25 cm
di = cm
5.Hard
Fdo​ = 25 cmR = 40 cm

An object is 25 cm in front of a concave mirror with a radius of curvature of 40 cm. Find the image distance di, positive for an image in front of the mirror (real) and negative for one behind it (virtual).

do = 25 cmR = 40 cm
di = cm
6.Hard
λ = ?d = 0.25 mmL = 1.5 m3.534 mm

Two slits 0.25 mm apart are lit with monochromatic light. On a screen 1.5 m away, bright fringe number 1 lies 3.534 mm from the central fringe. Find the wavelength λ.

d = 0.25 mmL = 1.5 my1 = 3.534 mmm = 1
λ = nm

Answer key

  1. 1. f = 500 Hz
  2. 2. f = 0.5 Hz
  3. 3. θc = 34.19 °
  4. 4. di = −11.11 cm
  5. 5. di = 100 cm
  6. 6. λ = 589 nm

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