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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
70°θ₂ = ?crown glass, n1​ = 1.50flint glass, n2​ = 1.62

A light ray in crown glass (n = 1.50) strikes a flat boundary with flint glass (n = 1.62) at 70° to the normal. Find the angle of refraction θ2, measured from the normal.

n1 = 1.50n2 = 1.62θ1 = 70°
θ2 = °
2.Easy
PI = 5 × 10⁻⁴ W/m²

The sound intensity near a lawn mower is 5 × 10⁻⁴ W/m². Find the sound intensity level β in decibels.

I = 5 × 10⁻⁴ W/m²I0 = 10⁻¹² W/m²
β = dB
3.Medium
θc = ?90°diamond, n1​ = 2.42acrylic, n2​ = 1.49

Light travels in diamond (n = 2.42) towards a flat boundary with acrylic (n = 1.49). Find the critical angle θc beyond which it is totally reflected.

n1 = 2.42n2 = 1.49
θc = °
4.Medium
Pβ = ?r = 20 m

A small loudspeaker radiates 0.2 W of sound power equally in all directions. Find the sound intensity level β at 20 m.

P = 0.2 Wr = 20 mI0 = 10⁻¹² W/m²
β = dB
5.Hard
θn1​ = 1.55n2​ = 1.47n0​ = 1.00

An optical fibre has a core with n₁ = 1.55 and a cladding with n₂ = 1.47. Find its numerical aperture NA.

n1 = 1.55n2 = 1.47
NA =
6.Hard
λ = ?d = 0.5 mmL = 2.5 m9 mm

Two slits 0.5 mm apart are lit with monochromatic light. On a screen 2.5 m away, bright fringe number 4 lies 9 mm from the central fringe. Find the wavelength λ.

d = 0.5 mmL = 2.5 my4 = 9 mmm = 4
λ = nm

Answer key

  1. 1. θ2 = 60.47 °
  2. 2. β = 86.99 dB
  3. 3. θc = 38 °
  4. 4. β = 76 dB
  5. 5. NA = 0.4915
  6. 6. λ = 450 nm

Full step-by-step solutions: practise this topic on examproblems.com.