Waves Flashcards
What two conditions are required for total internal reflection?
• Angle of incidence has to be larger than the critical angle
• Light has to travel from a more optically dense medium to a less dense medium
What is polarisation?
When light waves are restricted to 1 plane of oscillation.
What are the characteristics of transverse waves?
• can be polarised
• oscillate perpendicular to the direction of travel
• can refract, reflect and detract
What is the purpose of cladding in fibre optics?
• Reduces light lost
• Traps the light in the core with total internal reflection
How do we test for polarisation?
You use 2 polarisation filters- when the directions don’t align, the intensity will = 0. When they do, we will get maximum intensity.
State the definition for period
The time it takes for one complete pattern of oscillation to take place at any point.
What is the definition for frequency?
The number of oscillations per unit time at any point. F= 1/T
What is the definition for wavelength?
The distance between two successive identical points that have the same pattern of oscillation.
What is the definition for displacement?
The distance any part of the wave has moved from its mean or rest position. (Negative or positive)
What is the definition for amplitude?
The maximum displacement- the distance from a peak or trough to the mean rest position.
What is phase difference?
The difference in motion of the particles in a wave.
What is constructive interference?
When the path difference is a multiple of the wavelength so the angle is 0 degrees.
What is destructive interference?
When the path difference isn’t a multiple of the wavelength so the angle is 180 degrees.
What is coherence?
When waves have a constant phase difference.
What is superposition?
When 2 waves interact, the resultant displacement is the vector sum of the individual displacements.
