IB Physics: C2: Waves Day 1

Kinds of waves

Air, light, seismic, microwaves, particle, electromagnetic, ocean, sound, sine/cosine

Period

The time duration of one wave cycle

Amplitude

The maximum displacement from the center line (height of the wave)

Phase

The initial angle or point of the wave at the start

Travelling wave

An oscillation that transfers energy but not matter

Medium

The substance that waves go through

Longitudinal waves

Waves where particle motion is in the same direction of energy transfer

Pressure waves

Another name for longitudinal waves

Compression

The close-together areas in a longitudinal wave

Rarefaction

The far-apart areas in a longitudinal wave

Examples of waves

Air, light, seismic, microwaves, particle, electromagnetic, ocean, sound, sine/cosine

Wave Graph X-axis

Represents Time

Wave Graph Y-axis

Represents Angle (or displacement)

Period (Visual definition)

The horizontal length of one complete wave cycle (e.g., from peak to peak)

Amplitude (Visual definition)

The vertical distance from the center equilibrium line to the maximum height (peak)

Phase (Visual definition)

The specific starting point or angle of the wave at the beginning of the axis

Travelling wave

An oscillation that transfers energy but not matter

Medium

The substance or material that waves go through

Longitudinal waves

Waves where particle motion is in the same direction as the energy transfer

Pressure waves

An alternative name for longitudinal waves

Visual representation of Longitudinal Waves

Depicted as rows of dots (particles) that alternate between being clustered tightly and spread far apart

Compression

The specific areas in a longitudinal wave where particles are close together (high pressure)

Rarefaction

The specific areas in a longitudinal wave where particles are far apart (low pressure)

Direction of energy transfer (Longitudinal)

Parallel to the particle motion (often shown with a horizontal double arrow

Intensity (I)

Power per unit area (Formula: I = P / A)

SI Units for Intensity

Watts per meter squared (W/m²)

Wavefronts

Lines or surfaces representing the crests of a wave (depicted as concentric circles expanding from a source)

Spherical Wave Area

The surface area of a sphere, calculated as 4πr²

Intensity vs. Distance relationship (Spherical waves)

Intensity is inversely proportional to the square of the distance (I ∝ 1/r²)

Plane Waves

Waves observed far from the source where the wavefronts appear flat and parallel

Intensity behavior in Plane Waves

Intensity remains constant (does not diminish with distance)

Rays

Arrows drawn to indicate the direction of wave motion/propagation

Relationship between Rays and Wavefronts

Rays are always perpendicular (at right angles) to the wavefronts

Positive Displacement (Longitudinal Graph)

Represents particle position shifted to the right

Negative Displacement (Longitudinal Graph)

Represents particle position shifted to the left

Visualizing Longitudinal Graphs

The vertical Y-axis (Displacement) represents the horizontal shift of the particles (dots) from their equilibrium position

Graph-to-Particle Connection

Vertical dotted lines are used to map the position on the sine wave to the specific location of the particle below