Grade 10 physics – Properties of Waves Quiz

Wavelength is the spatial distance between two successive points that are in phase, such as crest to crest or trough to trough.

Frequency is the number of complete wave cycles that pass a fixed point each second and is measured in hertz (Hz).

The period is the time for one full cycle; it is the reciprocal of frequency (T = 1/f).

Wave speed v = frequency × wavelength, so v = 50 Hz × 2 m = 100 m/s.

Amplitude is the maximum distance particles move from the rest (equilibrium) position; it relates to energy and loudness.

In transverse waves (e.g., waves on a string, surface water waves), particles oscillate at right angles to the wave's propagation direction.

Sound waves in air are longitudinal: air particles oscillate back and forth in the same direction the wave travels, forming compressions and rarefactions.

Sound in air is longitudinal because the air molecules vibrate along the direction of wave travel, producing compressions and rarefactions.

Frequency is measured in hertz (Hz), which equals one cycle per second.

For many mechanical waves the energy carried is proportional to the square of the amplitude (E ∝ A^2), so doubling amplitude increases energy by 2^2 = 4 times.

On reflection at a boundary the wave's frequency stays the same because frequency is determined by the source; other properties like amplitude may change.

Constructive interference happens when waves are in phase (phase difference 0° or multiples of 360°), so their displacements add to give a larger amplitude.

Nodes are fixed points in a standing wave where destructive interference causes the displacement to remain zero.

Antinodes are points in a standing wave where constructive interference gives the largest oscillation (maximum amplitude).

Pitch is how high or low a sound seems and depends on the sound's frequency: higher frequency → higher pitch.

Loudness relates to the energy and intensity of the sound; larger amplitude means greater energy and a louder sound.

When the source moves towards the observer, successive wavecrests reach the observer more often, so the observed frequency (pitch) is higher.

Refraction is the change in direction of waves when they enter a medium in which their speed is different, causing the wave to bend.

Diffraction occurs when waves encounter edges or slits comparable in size to their wavelength and spread into the region beyond.

Waves transmit energy and information but do not have mass; amplitude, frequency and wavelength are standard wave properties.

A wavefront connects points that have the same phase (e.g., all crests) and helps describe the wave's propagation direction.

Huygens' principle explains wave propagation: every point on a wavefront can be considered as emitting secondary wavelets whose envelope gives the new wavefront.

For longitudinal waves on a slinky, wavelength is the distance between repeating features in phase, such as compression to the next compression.

Wavelength λ = v / f = 340 m/s ÷ 680 Hz = 0.5 m.

Electromagnetic waves do not require a medium and can travel through a vacuum; mechanical waves like sound need a material medium.