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.

A wave is a disturbance that carries energy (and information) through a medium or space, while the medium's particles generally oscillate about fixed positions and are not transported with the wave.

Transverse waves have particle or field oscillations perpendicular to the direction of wave travel; light is an electromagnetic transverse wave. Sound and compressions in a slinky are longitudinal, and a stream carrying leaves is bulk motion of matter.

Wave speed equals frequency times wavelength (v = fλ). This comes from how many wavelengths pass a point per second (frequency) multiplied by the length of each wavelength.

Period T is the reciprocal of frequency: T = 1/f. For f = 50 Hz, T = 1/50 = 0.02 s.

Amplitude is the maximum displacement of a particle from its equilibrium position in a wave; it is related to the energy carried by the wave.

For many waves (e.g., mechanical and electromagnetic), the energy transported is proportional to the amplitude squared (E ∝ A^2), so doubling amplitude gives four times the energy.

When a wave crosses a boundary between media, its frequency remains the same because oscillations at the boundary must match; wavelength and speed change to satisfy v = fλ.

Nodes are fixed points on a standing wave where destructive interference keeps displacement at zero. Antinodes are points of maximum displacement.

The principle of superposition states that overlapping waves combine by algebraic addition of displacements; this can produce constructive or destructive interference but does not permanently alter the individual waves.

Diffraction is the spreading or bending of waves when they encounter an obstacle or pass through an aperture, especially noticeable when the obstacle size is comparable to the wavelength.

The law of reflection states that the angle the incoming ray makes with the normal equals the angle the reflected ray makes with the normal; both measured from the normal to the surface.

Snell's law shows that when light goes from a less optically dense medium to a denser one (higher refractive index), its speed decreases and the ray bends toward the normal.

Total internal reflection happens only when light attempts to move from a medium with higher refractive index to one with lower index and the incidence angle is greater than the critical angle, causing no refracted ray.

Frequency is measured in hertz (Hz), which equals the number of complete oscillations or cycles that occur each second.

Crossing a boundary changes wave speed (different medium) and hence wavelength (v = fλ), but frequency remains the same because the source controls it.

Polarization restricts the oscillation direction of transverse waves; longitudinal waves (sound in air) oscillate in the direction of travel and cannot be polarized.

Beats occur when two waves of slightly different frequencies superpose, producing a modulation in amplitude at the beat frequency equal to the difference of the two frequencies.

Diffraction is strongest when the wavelength is comparable to or larger than the aperture; small wavelengths compared to the aperture produce little bending.

A wavefront is an imaginary surface connecting points on a wave that have the same phase (e.g., crests). Huygens' principle treats each point on a wavefront as a source of secondary waves.

Dispersion occurs because refractive index depends on wavelength; different colours travel at slightly different speeds in glass and bend by different angles, separating white light into a spectrum.

In longitudinal waves, the oscillations of particles are along the direction of energy propagation; compressions and rarefactions in sound are examples.

Coherence (constant phase difference) between the two waves is required for stable constructive and destructive interference; incoherent sources wash out the pattern.

For a point source emitting equally in all directions, intensity follows the inverse-square law (I ∝ 1/r^2) because the same energy is spread over an area that grows with r^2.

All electromagnetic waves travel at the constant speed c ≈ 3.0 × 10^8 m/s in vacuum, independent of frequency. Dispersion occurs only in materials, not in vacuum.

When the source moves toward the observer, successive wavefronts are compressed, increasing the frequency heard (higher pitch). When receding, frequency is lowered.

For a string fixed at both ends: fundamental (first harmonic) has wavelength λ1 = 2L; second harmonic (n=2) has λ2 = 2L/2 = L, so the wavelength of the second harmonic equals the string length.

Phase difference measures how much one point's oscillation is ahead or behind another in terms of fraction of a full cycle, usually expressed in degrees or radians (e.g., 180° is π radians).