Light Waves and Vibrations 1 & 2

What is an oscillation?

An oscillation is a repeated back-and-forth motion around a central point or equilibrium position.

Define simple harmonic motion (SHM).

A restoring force where acceleration is directly proportional to displacement and opposite in direction.

What three conditions must be met for SHM?

A mass, an equilibrium position, and a restoring force proportional to displacement.

What is the restoring force in SHM directly proportional to?

The displacement from equilibrium.

Give examples of systems that exhibit SHM.

Pendulums, springs, vibrating strings, and the human heartbeat (ECG signals).

What is a transverse wave?

A wave where the displacement is perpendicular to the direction of wave travel (e.g., light).

What is a longitudinal wave?

A wave where the displacement is parallel to the direction of wave travel (e.g., sound).

Define amplitude.

Maximum displacement from the equilibrium position.

Define wavelength.

Distance between two successive similar points on a wave (e.g., crest to crest).

Define frequency and period.

Frequency is how many oscillations per second (Hz); period is the time for one oscillation (s).

What is wave speed?

The distance a wave travels per unit time (speed = wavelength × frequency).

What factors determine the speed of a wave?

The medium's properties and wave type (e.g., sound vs. light).

What is the phase difference?

The amount by which one wave leads or lags another (in degrees or radians). It indicates the relative position of the waves in their cycle.

What is wave intensity?

Power transmitted per unit area, measured in watts per square meter (W/m²). It reflects the energy carried by the wave and its effect on the medium.

How does amplitude affect wave energy?

Energy is proportional to the square of amplitude.

How does intensity change as a wave travels?

As a wave travels, its intensity decreases due to the spreading of wave energy over a larger area and damping (absorption)

What are the three key aspects of sound waves?

Source, propagation through a medium, and detection. The source produces the sound, it travels through a medium such as air or water, and it is detected by a receiver, like the human ear.

What is the relationship between pitch and frequency?

Higher frequency = higher pitch; lower frequency = lower pitch.

What physical property is associated with loudness?

Intensity, related to amplitude.

In what type of medium does sound travel fastest?

Solids (then liquids, then gases).

What is ultrasound?

Sounds above 20,000 Hz, beyond human hearing.

What is the Doppler effect?

The change in frequency due to relative motion between source and observer. It causes a shift in the observed frequency of a wave when the source or observer is moving.

How does the frequency shift when a source moves toward or away from an observer?

Toward = higher frequency; away = lower frequency.

What causes a sonic boom?

A sudden high-pressure wave created when an object exceeds the speed of sound.

What is a shock wave?

A buildup of overlapping sound waves from a source moving faster than the speed of sound.

What is the superposition of waves?

When two waves overlap to form a new wave pattern.

What is constructive interference?

Wave crests and troughs align → amplitude increases. This occurs when two or more waves meet in phase, leading to a larger resultant wave.

What is destructive interference?

Crest meets trough → cancel each other out → amplitude = 0. This occurs when two waves are out of phase, leading to a reduction of overall wave amplitude.

What are the conditions for interference?

Waves must be coherent (constant phase difference) and monochromatic (same wavelength).

What is a standing wave?

A wave pattern that appears stationary due to continuous interference.

Define nodes and antinodes in a standing wave.

Nodes: points that stay still; Antinodes: points of maximum motion.

What is diffraction?

The bending and spreading of waves around obstacles or through openings.

What is refraction?

The change in direction of a wave as it passes from one medium to another, caused by a change in its speed.

What does Huygens’s Principle state?

Every point on a wavefront is a source of wavelets that spread out in the forward direction at the wave speed.

What is Rayleigh’s Criterion?

The minimum angular separation at which two point sources are distinguishable. It describes the ability of an optical system to resolve two closely spaced objects based on their diffraction patterns.