Waves Flashcards
What are the two types of waves?
Transverse (oscillations perpendicular to direction, e.g., light) and longitudinal (oscillations parallel, e.g., sound).
Define amplitude.
Maximum displacement of a wave from its rest position (measured in meters, m).
Define wavelength.
Distance between two consecutive points in phase (e.g., crest to crest) in meters (m).
Define frequency.
Number of waves passing a point per second (measured in Hertz, Hz).
What is the wave speed equation?
Wave speed (m/s) = frequency (Hz) × wavelength (m). [On equation sheet]
How is time period related to frequency?
Time period (s) = 1 ÷ frequency (Hz). [On equation sheet]
What is reflection of waves?
When a wave bounces off a surface (e.g., light in mirrors, echoes for sound).
What is refraction?
Change in wave direction when it enters a medium with a different speed (e.g., light bending in water).
What is diffraction?
Spreading of waves around obstacles/gaps. Greatest when gap ≈ wavelength.
List the electromagnetic spectrum in order.
Radio → Microwaves → Infrared → Visible light → Ultraviolet → X-rays → Gamma rays.
What are uses of radio waves?
Broadcasting (TV/radio) and communications.
What are dangers of ultraviolet (UV)?
Skin damage, eye cataracts, and increased skin cancer risk.
How do sound waves travel?
As longitudinal waves requiring a medium (solid, liquid, gas). Cannot travel in a vacuum.
What is ultrasound?
Sound waves above 20,000 Hz. Used in medical imaging (e.g., prenatal scans) and sonar.
How do you calculate distance using echoes?
Distance = (speed of sound × time) ÷ 2 (accounts for to-and-fro journey).
What is infrared radiation?
EM waves emitted by hot objects. Used in thermal imaging and heaters.
What is a black body radiator?
An object that absorbs all radiation and emits radiation across a range of wavelengths.
What are seismic waves?
Waves produced by earthquakes. P-waves (longitudinal) and S-waves (transverse).
How do P and S waves differ?
P-waves travel through solids/liquids; S-waves only solids. Helps study Earth’s core.
What is the Doppler effect?
Change in observed frequency/wavelength when source moves relative to observer (e.g., sirens passing by).
What affects pitch and loudness of sound?
Pitch = frequency; Loudness = amplitude.
How to measure wave speed with a ripple tank?
Measure wavelength (using ruler), frequency (count waves/time), then use v = f × λ.
What is the law of reflection?
Angle of incidence = angle of reflection (true for all waves).
How does surface color affect infrared emission?
Darker/matte surfaces emit infrared more effectively; shiny surfaces reflect it.
