Waves Flashcards
What is phase difference?
A measure of the separation of two points on a wave as a fraction of wavelength expressed as an angle in radians.
How are stationary waves formed?
By the interference of two waves of the same frequency and amplitude, travelling in opposite direction.
Describe the disturbance at nodes.
Zero disturbance
Describe the disturbance at antinodes.
Maximum disturbance
When is interference produced?
When coherent waves overlap.
What is a coherent wave?
Constant phase difference/relationship.
Formula for constructive path difference?
m λ
Formula for destructive path difference?
m+1/2 λ
What happens when a wave passes through a medium such as glass?
It’s wavelength and speed decrease due to refraction.
When does a phase change of pi occur?
When light reflects off a medium with a higher refractive index (doesn’t occur when it reflects off a lower refractive index)
How can you produce interference patterns?
By taking one light wave and splitting it into two waves by reflection and refraction, then combine these two waves later.
What is an example or division of amplitude?
A thin film of oil on a puddle of water appearing multicoloured.
What is thin wedge interference?
When a thin wedge of air between two glass plates will produce interference fringes by division of amplitude.
What is Brewster’s angle?
Angle of incidence which causes the reflected light to be fully polarised.
Explain polarisation.
Unpolarised light has oscillations in every plane perpendicular to its direction of travel.
Polarising material allows the transmission of light in one direction only.
Plane polarised light oscillates in one plane only.
As the analyser is rotated, transmission of the polarised light will increase until the angle of rotation is 90 degrees.
Only transverse waves can be polarised.
