Physics - Module 3

displacement

The distance a particle has travelled from its equilibrium position

Amplitude

Maximum displacement of a particle from the equilibrium position Unit M

Frequency

Number of crests (or compressions) that passes a point in 1 second Unit Hz

Wavelength

Distance between successive crests or troughs Unit m

Period

The time it takes before a wave repeats itself or completes one full cycle. Unit s

speed

Distance travelled per second

Wave

A disturbance that transfers energy through matter or space

Phase difference

Phase difference is equal to the distance between the two points divided by the wavelength

Longitudinal wave

The particles in the wave oscillate parallel and antiparallel to the direction of energy transfer

Transverse wave

The particles in the wave oscillate perpendicular to the direction of energy transfer

Mechanical wave

A wave that requires a medium to propogate

Electromagnetic wave

Does not require a medium to propagate c=3×10^8 m/s

Reflection

Wave bounces off a surface. Angle of incidence = angle of reflection. Speed, frequency, and wavelength are unchanged.

Refraction

Wave changes speed (and wavelength) when moving between media, causing a change in direction. Frequency is always unchanged.

Diffraction

Wave spreads out after passing through a gap or around an obstacle. Most pronounced when gap width ≈ wavelength.

Superposition

When two waves overlap, the net displacement equals the algebraic sum of the individual displacements at every point.

Constructive interference

Two waves add together (crests align) → amplitude increases.

Destructive interference

Waves cancel (crest meets trough) → amplitude decreases or reaches zero.

Standing wave

Formed when two identical waves travel in opposite directions and superpose. No net energy transfer. Pattern has nodes (zero amplitude) and antinodes (maximum amplitude).

Node

Point of permanent zero displacement in a standing wave — always destructive interference.

Antinode

Point of maximum displacement in a standing wave — always constructive interference.

Wave speed

Wave speed = Frequency X Wavelength v = fλ

Period —> frequency

f = 1 / T they are inversly proportional

Resonance

Occurs when the driving frequency equals the natural frequency of a system. Amplitude is maximised and energy transfer is most efficient.

Total internal Reflection

Occurs when light is traveling from a dense to a less dense medium. higher n to lower n