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

Light travels at 2.01 × 10⁸ m/s in a transparent material. Find its refractive index n.

v = 2.01 × 10⁸ m/sc = 3.00 × 10⁸ m/s

n =

2.Easy

A sound wave in water has a frequency of 200 Hz and travels at 1480 m/s. Find its wavelength λ.

f = 200 Hzv = 1480 m/s

λ = m

3.Medium

An object stands 18 cm in front of a thin converging lens with a focal length of 5 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 = 18 cmf = 5 cm

d_i = cm

4.Medium

An object stands 6 cm in front of a thin converging lens with a focal length of 10 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 = 6 cmf = 10 cm

d_i = cm

5.Hard

A sensor at rest sends ultrasound of 25 kHz towards a car that approaches at 10 m/s and mixes the echo with the emitted signal. Find the beat frequency f_b (speed of sound 343 m/s).

f = 25 kHzu = 10 m/sv = 343 m/s

f_b = Hz

6.Hard

Light of wavelength 450 nm falls at right angles on a grating with 800 lines per millimetre. Find the angle θ₂ of the order-2 maximum.

N = 800 mm⁻¹λ = 450 nmm = 2

θ₂ = °

Answer key

1. n = 1.493
2. λ = 7.4 m
3. d_i = 6.923 cm
4. d_i = −15 cm
5. f_b = 1502 Hz
6. θ₂ = 46.05 °

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