Waves and Particle Nature of Light Flashcards
Describe the difference between longitudinal and transverse waves?
Longitudinal waves oscillate in parallel to its direction of propagation.
Whilst transverse waves oscillate in parallel to its direction of propagation.
Describe the difference between mechanical and electromagnetic waves?
Mechanical waves require a medium to travel through whilst electromagnetic waves are constantly varying electric and magnetic fields.
Show that the units on both sides of the wave equation are consistent?
wave speed (ms⁻¹) = frequency (Hz) x wave length (m)
v = fλ v = (¹/period)λ
ms⁻¹ = (¹/s)m
= ms⁻¹
What is rarefaction?
When particles are spread out in a longitudinal wave.
What is compression?
When particles are close together in a longitudinal. wave?
Why is there a variation in pressure as a longitudinal wave passes a point?
Because to travel the wave need to go through rarefaction and compression.
Is there is a pressure variation from transverse waves?
No.
Define amplitude.
The maximum displacement from the mean position (in meters).
Define period.
The time taken for one complete oscillation (in seconds)
Define frequency.
The number of waves per second (Hz).
Define oscillation.
The repetitive motion about an equilibrium point, with the object at rest at the maximum displacement.
Define displacement.
The position of a particular point on a wave, at a particular instant, measured from the mean (equilibrium).
Define wavelength.
The distance between a point on a wave and the same point on the next cycle of the wave.
What is at the end of a positive amplitude?
A peak/crest.
What is at the end of a negative amplitude?
A trough.
Other than the wave equation, How else can wave speed be calculated?
Distance a single crest (or another point on the waveform) travels / time taken.
Define phase.
The phase of an oscillation refers to the position within a cycle that a given point occupies, relative to the onset of the cycle.
Define a radian.
The angle subtended by an arc which is equal in length to the radius.
1 rad ≈
57.296⁰
π rad =
180⁰
A full circle = ___⁰ = __ rad
= 360⁰ = 2π rad
antiphase =
180⁰ or π rad out of phase.
What is the phase difference between two crests?
In perfect phase.
What is the phase difference between a crest and the next trough?
In antiphase (180⁰ or π rad out of phase).