Wave Properties — Drills · Grade 12 Science

Chapter: Waves, Sound & Optics

What these drills covers

By the end of Wave Properties you should be able to:

I can distinguish transverse from longitudinal waves and identify amplitude, wavelength, frequency, and period.
I can relate frequency, wavelength, and speed using v = f λ, and predict the result of two waves interfering.

6 questions, numeric, multiple choice and written answer, each with a worked explanation.

Vocabulary used: wave, transverse wave, longitudinal wave, amplitude, wavelength (λ), frequency (f), interference.

Problem 1

A wave has a frequency of 15 Hz and a wavelength of 2 m. Find its speed.

Answer and explanation

30 m/s

v = f × λ = 15 × 2 = 30 m/s.

Problem 2

A wave has a period of 0.02 s. Find its frequency.

Answer and explanation

50 Hz

f = 1 ÷ T = 1 ÷ 0.02 = 50 Hz.

Problem 3

A wave travels at 20 m/s with a frequency of 5 Hz. Find its wavelength.

Answer and explanation

4 m

λ = v ÷ f = 20 ÷ 5 = 4 m.

Problem 4

A wave's energy is proportional to the square of its amplitude. If you double the amplitude, the energy becomes…

the same
four times as much
one quarter as much
half as much

Answer and explanation

four times as much

Energy ∝ amplitude², so doubling the amplitude multiplies the energy by 2² = 4.

Problem 5

Explain the difference between a transverse and a longitudinal wave, and give an example of each.

Answer and explanation

In a transverse wave the particles vibrate perpendicular to the direction the wave travels — for example a wave on a rope or a light wave. In a longitudinal wave the particles vibrate parallel to the wave's travel, forming compressions and rarefactions — for example a sound wave.

Problem 6

A wave travels at 750 m/s with a frequency of 250 Hz. Find its wavelength.

Answer and explanation

3 m

λ = v ÷ f = 750 ÷ 250 = 3 m.

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