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

The sound intensity near a lawn mower is 2.5 × 10⁻⁴ W/m². Find the sound intensity level β in decibels.

I = 2.5 × 10⁻⁴ W/m²I₀ = 10⁻¹² W/m²

β = dB

2.Easy

A light ray in crown glass (n = 1.50) strikes a flat boundary with flint glass (n = 1.62) at 25° to the normal. Find the angle of refraction θ₂, measured from the normal.

n₁ = 1.50n₂ = 1.62θ₁ = 25°

θ₂ = °

3.Medium

An object stands 4 cm in front of a thin converging lens with a focal length of 30 cm. Find the image distance d_i. Use the sign convention 1/f = 1/d_o + 1/d_i (f < 0 for a diverging lens, d_i < 0 for a virtual image).

d_o = 4 cmf = 30 cm

d_i = cm

4.Medium

A pipe closed at one end is 1.2 m long. The speed of sound is 343 m/s. Find the frequency f₃ of its harmonic number 3.

v = 343 m/sn = 3L = 1.2 m

f₃ = Hz

5.Hard

Two thin lenses share an axis, 60 cm apart: lens 1 with f₁ = 15 cm and lens 2 with f₂ = 5 cm. An object stands 18 cm in front of lens 1. Find the position d_i2 of the final image measured from lens 2 (positive beyond lens 2, real-is-positive convention).

f₁ = 15 cmf₂ = 5 cms = 60 cmd_o = 18 cm

d_i2 = cm

6.Hard

An object is 5 cm in front of a concave mirror with a radius of curvature of 24 cm. Find the image distance d_i, positive for an image in front of the mirror (real) and negative for one behind it (virtual).

d_o = 5 cmR = 24 cm

d_i = cm

Answer key

1. β = 83.98 dB
2. θ₂ = 23.04 °
3. d_i = −4.615 cm
4. f₃ = 214.4 Hz
5. d_i2 = 4.286 cm
6. d_i = −8.571 cm

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