Physics Chapter 4 Flashcards
What is meant by monochromatic?
Waves that have the same frequency/ wavelength
What is meant by coherent?
Waves that have a constant phase difference
Define wavelength
The distance that a wave moves in the time that a particle completes one full oscillation
State the difference between a transverse wave and a longitudinal wave.
In a transverse wave, the direction of oscillation is perpendicular to the direction of energy transfer.
In a longitudinal wave, the direction of oscillation is parallel to the direction of energy transfer.
State the principle of superposition as applied to waves.
The total displacement when waves meet is equal to the vector sum of the individual wave displacements at that point.
When an unpolarised wave of intensity I passes through two polarising filters, with the second one at θ to the first one, what is the resultant intensity Ifinal?
State two differences between a travelling wave and a standing wave.
Amplitude:
Particles in travelling waves vibrate with a same amplitude, but particles in standing waves vibrate in different amplitudes
Phase difference:
Particles in travelling waves always do not vibrate in phase, and the particles in the same loop vibrate in phase, and vibrate in antiphase with the particles in the adjacent loop
Energy:
Energy is transmitted from one end to the other end in travelling waves, and energy is localized in standing waves
Displacements:
Particles in travelling waves reach their respective maximum displacements at different times, and particles in standing waves reach their respective maximum displacement at the same time
Outline the conditions for the formation of a standing wave
For a standing wave to form, there has to be two waves with equal amplitude, frequency and speed but travelling in opposite directions. When the waves meet and superimpose on each other, a standing wave will be formed.
Outline what is meant by diffraction. [2]
Diffraction is the phenomenon of the spreading out of a wave [1] when it meets an obstacle. [1]
State how a standing wave is formed. [2]
It is formed by the superposition of two travelling waves [1] of the same speed and same amplitude in opposite direction. [1]
On a string: «travelling» wave moves along the length of the string and reflects «at fixed end» [1]
superposition/interference of incident and reflected waves [1]
Reference: TZ1 M21 HL P2 Q8a
