Wave and light

7 Quantities that defines a wave

Amplitude, wavelength, frequency, period, wave speed, crest, trough

Amplitude

Height of the wave; measures energy.

Wavelength

Distance between two crests or compressions.

Frequency

Number of waves passing a point per second.

Period (T)

Time for one full wave to pass a point.

Wave speed (v)

How fast the wave travels.

Crest

Highest point of a transverse wave.

Trough

Lowest point of a transverse wave.

Amplitude (Symbol, unit and unit symbol)

A, meters, m

Wavelength (Symbol, unit and unit symbol)

Lambda, meters, m

Frequency (Symbol, unit and unit symbol)

f, hertz, Hz

Period (Symbol, unit and unit symbol)

T, seconds, s

transverse wave and example

Particles move up and down at right angles to the direction of the wave. Light waves, water waves.

longitudinal wave and example

Particles move back and forth parallel to the direction of the wave. Sound waves.

What type of wave is light?

Transverse , it travels as electric and magnetic fields; does not need a medium.

What type of wave is sound?

Longitudinal caused by vibrations; needs a medium to travel.

What is a mechanical wave?

A wave that transfers energy through vibrations of particles, it requires a medium to move.

Why can’t sound travel in space?

There’s no particles for vibrations to pass through.

In which state do waves travel fastest?

Solids  because particles are closely packed, so vibrations transfer energy more quickly.

What does convergent mean?

Rays or waves come together

In which state do waves travel slowest?

gases as particles are far apart

What does divergent mean?

Rays or waves spread apart

What is the focal point?

The point where light rays meet after reflection or refraction.

How does light travel?

Light always travels in a straight line through a uniform medium

What is the law of reflection?

Angle of incidence = Angle of reflection

• Incident ray = incoming light

• Reflected ray = outgoing light

• Normal line = 90° to the surface

How do you measure angles of incidence and reflection?

• Draw a normal line at 90° to the mirror.

• Measure angle of incidence (i) between the incident ray and normal.

• Measure angle of reflection (r) between the reflected ray and normal.

What happens when light hits a flat mirror?

Light reflects evenly — the image appears upright, same size, and laterally inverted (left ↔ right swapped).

What happens when light passes through a prism?

Light bends (refracts) and splits into colours (red → violet).
This is called dispersion, because each colour travels at a slightly different speed.