Properties of waves Flashcards – AQA GCSE Combined Science: Trilogy (8464) — Physics — Foundation

What is the approximate speed of sound in air?

$330–350\ \mathrm{m/s}$

How is speed calculated from distance travelled and time taken?

$v = \frac{d}{t}$

A distant source produces a sound and a visible signal at the same time. What distance and time are measured to estimate the speed of sound?

Measure the distance from the source to the observer and the time between seeing the signal and hearing the sound.

Why can the time between seeing a distant signal and hearing its sound be treated as the sound travel time?

The light travel time is negligible compared with the sound travel time.

How can repeated measurements improve an estimate of the speed of sound in air?

Repeat the measurement and average the results.

What is a progressive wave?

A travelling disturbance that transfers energy from one place to another.

How do particles in a material medium move as a progressive wave passes?

They oscillate about their equilibrium positions; they do not travel along with the wave.

What is the amplitude of an oscillating particle?

Its maximum displacement from its equilibrium position.

What is the frequency of a wave?

The number of complete oscillations per unit time.

What is the period of a wave?

The time for one complete oscillation.

How are frequency $f$ and period $T$ related?

$f = \frac{1}{T}$

What is the wavelength of a wave?

The distance between successive points at the same stage of oscillation.

What is wave speed?

The distance travelled by the disturbance per unit time.

How far does a progressive wave travel in one period?

One wavelength.

How are wave speed $c$, frequency $f$ and wavelength $\lambda$ related?

$c = f\lambda$