Booklet 2B - Waves (Factual) Flashcards
What is the frequency of a wave?
The number of waves per second.
What is the wavelength of a wave?
Wavelength is the distance from a point on one wave to the same point on the next wave.
What is the period of a wave?
The time it takes one wave to pass a point.
What is the amplitude of a wave?
The distace from the centre of a wave (the line of zero disturbance) to the crest or trough.
What is meant by diffraction?
Diffraction is the bending of waves round an object or through a gap.
What will increase the amount of diffraction?
- Longer wavelengths diffract more
- Narrower gaps cause more diffraction
What is a coherent source?
Waves that have a constant phase relationship.
What is constructive intereference?
This occurs when two waves meet at a point in phase.
This results in a wave of larger amplitude.
What is destructive interference?
Destructive interference occurs when two waves meet at a point exactly 180º out of phase.
This results in smaller amplitude (zero if two waves are identical).
What is the test for a wave?
If it can cause interference.
Describe the interference pattern produced by a monochromatic light source and a double slit.
A series of bright and dark fringes symmetrical about the central, brightest fringe.
What is a minimum?
A point where destructive interference occurs e.g. dark, quiet.
What is a maximum?
A point where constructive interference occurs e.g. bright, loud.
What are the conditions for constructive interference in terms of path difference?
The path difference is a whole number of wavelengths.
(0, 1λ, 2λ, 3λ…)
What are the conditions for destructive interference in terms of path difference?
The path difference is an odd number of half wavelengths.
(½λ, 1½λ, 2½λ…)
What are the advantages of using a grating to produce an interference pattern instead of a double slit?
- Fringes are brighter
- Fringes are sharper
Using a grating how can you increase the spacing between the maxima?
- Use a grating with a smaller slit separation.
- Use a source with a greater wavelength of light
- Move the screen further away