4: Waves - YK Flashcards
(10 cards)
What is a wave?
A disturbance which carries energy from one point to another
What is the difference between a transverse and longitudinal wave?
Transverse: disturbance perpendicular to direction of movement
Longitudinal: disturbance parallel to direction of movement
What are examples of transverse and longitudinal waves?
Transverse: EM waves (light), water waves, waves on a rope
Longitudinal: Sound waves, longitudinal waves on a spring
What are mechanical waves?
Waves that move energy through vibration of molecules so require a medium to travel through
What are electromagnetic waves?
Self-propagating waves (don’t need a medium) made up of alternating electric and magnetic fields
What is a cycle?
The disturbance produced by one oscillation of the wave source, it is the repeating unit of the wave
Transverse: each cycle has a crest and trough (highest and lowest point)
Longitudinal: each cycle has a compression and rarefaction
What are the wavelength (λ), amplitude (A), frequency (f), period (T), and velocity (c) of a wave?
λ: distance from a point on one cycle to the corresponding point on an adjacent cycle
A: maximum displacement of any particle from its undisturbed position
f in Hz: number of cycles passing a point in 1 second
T: time taken for one cycle to pass a point
c: distance travelled by one cycle in one second
What are the formulas linking T + f, and c + f + λ?
T = 1/f c = fλ
What is reflection?
When a wave bounces off an obstacle, f + c + λ stay same but A can be reduced, when a wave reflects a crest becomes a trough and vice versa
What is refraction?
Change in speed and direction of a wave when it passes from medium to another
Passing into slower material (lower refractive index), wavelength decreases, wave bends away from normal
Passing into faster material (higher refractive index), wavelength increases and wave bends towards normal
