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
PI = 6 × 10⁻² W/m²

The sound intensity near a rock concert is 6 × 10⁻² W/m². Find the sound intensity level β in decibels.

I = 6 × 10⁻² W/m²I0 = 10⁻¹² W/m²
β = dB
2.Easy
λ = ?v = 3.00 × 10⁸ m/sf = 102.3 MHz

A radio wave has a frequency of 102.3 MHz and travels at 3.00 × 10⁸ m/s. Find its wavelength λ.

f = 102.3 MHzv = 3.00 × 10⁸ m/s
λ = m
3.Medium
L = 1 mn = 4

A pipe open at both ends is 1 m long. The speed of sound is 343 m/s. Find the frequency f4 of its harmonic number 4.

v = 343 m/sn = 4L = 1 m
f4 = Hz
4.Medium
θc = ?90°diamond, n1​ = 2.42crown glass, n2​ = 1.50

Light travels in diamond (n = 2.42) towards a flat boundary with crown glass (n = 1.50). Find the critical angle θc beyond which it is totally reflected.

n1 = 2.42n2 = 1.50
θc = °
5.Hard
θa​ = ?n1​ = 1.52n2​ = 1.51n0​ = 1.00

An optical fibre has a core with n₁ = 1.52 and a cladding with n₂ = 1.51. Find the largest angle θa to the fibre axis at which light from air can enter the end of the fibre and still be guided by total internal reflection.

n1 = 1.52n2 = 1.51n0 = 1.00
θa = °
6.Hard
λ = 500 nmd = 0.3 mmL = 3 my = ?

Light of wavelength 500 nm falls on two slits 0.3 mm apart. The screen is 3 m away. Find the distance y2 from the central bright fringe to bright fringe number 2.

λ = 500 nmd = 0.3 mmL = 3 mm = 2
y2 = mm

Answer key

  1. 1. β = 107.8 dB
  2. 2. λ = 2.933 m
  3. 3. f4 = 686 Hz
  4. 4. θc = 38.3 °
  5. 5. θa = 10.02 °
  6. 6. y2 = 10 mm

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