physics

Doppler Effect

Causes apparent frequency shifts for moving sources (higher as approaching, lower as receding).

Beats

Occur when two close frequencies interfere, producing rhythmic loud/soft cycles.

Visible light spectrum

Red (low frequency) → Violet (high frequency); beyond violet lies ultraviolet, X-rays, and gamma rays.

Transparent materials

Like glass, allow light through via absorption and re-emission.

Opaque materials

Absorb and heat up.

Rods and cones

The eye uses these to detect brightness and color; the fovea gives sharp vision.

Optic nerve

Sends signals to the brain.

Waves

Transfer energy without transferring matter; vibration is the source.

Transverse waves

Move particles perpendicular to the wave direction (e.g., light, water).

Longitudinal waves

Move particles parallel to the wave direction (e.g., sound).

Sound

Mechanical wave that needs a medium (solid, liquid, gas).

Light

Electromagnetic wave that needs no medium.

Wave speed

Depends on the medium; sound travels fastest in solids (v = fλ).

Standing waves

Form by interference; nodes = no motion, antinodes = maximum motion.

Transverse wave

Medium vibrates perpendicular

Doppler effect

Changes frequency as source approaches

Longitudinal wave

Medium vibrates parallel

Echolocation

Dolphins use this to navigate and find food

Opaque Materials

Absorb light, convert to heat

Umbra

Full shadow

Penumbra

Partial shadow

Fovea

Area of sharp vision in the eye

Blind spot

Area in the eye with no photoreceptors

Electromagnetic Waves

Vibrating electric and magnetic fields

Electromagnetic Spectrum

Radio → Microwave → IR → Visible → UV → X-rays → Gamma

Speed of Sound

0°C: -330 m/s, increases 0.6 m/s per °C rise

Pitch

Frequency perception

Standing Waves

Nodes: No displacement, Antinodes: Maximum displacement

Constructive Interference

Add amplitudes

Destructive Interference

Cancel amplitudes

Bow Wave

V-shaped wave created by an object moving through a medium

Shock Wave

Cone-shaped wave, produces a sonic boom

Normal range of human hearing

20 Hz - 20,000 Hz

Wave speed

Calculated as wavelength multiplied by frequency

Beats

Alternating loud/soft sounds from close frequencies

Resonance

Occurs when forced vibrations match natural frequency

Sound cannot travel in space

Space has strong magnetic fields, light blocks sound, temperature is too low.

Electromagnetic waves consist of

Static electric fields.

Frequency arrangement

X-rays, Visible Light, Infrared, Radio Waves arranged by increasing frequency.

Speed of sound wave

A sound wave has a frequency of 440 Hz and a wavelength of 0.78 meters, resulting in a speed of 500 m.

Vibration

A wiggle in time.

Wave

A wiggle in both space and time.

Pendulum period dependency

The period depends mainly on the length of the string.

Amplitude

Height from the centerline to a crest.

Wave frequency and period

If a wave has a frequency of 5 Hz, its period is 0.2 seconds.

Longitudinal wave example

Sound wave.

Constructive interference

Results in a larger amplitude.

Wave speed formula

Wave speed (v) is calculated as v = fλ.

Crest

The highest point of a wave.

Trough

The lowest point of a wave.

Wavelength

The distance between two crests.

Frequency (Hz)

The number of waves per second.

Period (T)

Calculated as T = 1/f.

Vibrating water molecules

Not a characteristic of electromagnetic waves.

High pitch sound

Determined by high frequency.

Longer pendulum effect

A longer pendulum results in a longer period.

Mass effect on pendulum

Mass does not affect the period of a pendulum.