Unit 2 - Waves Flashcards
A scientist discovers a seismic wave that is polarised. State and explain what can be deduced from this. (2)
- Transverse
* Only transverse waves can be polarised
What two conditions are required for total internal reflection. (2)
- n1 > n2
* Angle > critical angle
Define the frequency of a progressive wave. (1)
• Number of waves passing a point per second
Explain the meaning of the term monochromatic light. (1)
Single frequency or wavelength
State and explain one precaution that should be taken when using laser light. (2)
- Don’t shine towards person/ avoid reflections
* Causes eye damage
Give two reasons why optical fibres used for communications have cladding. (2)
(Any two)
Protect core from scratching/ prevent crossover of signal/ increase critical angle/ reduce multipath dispersion
Explain what is meant by coherent sources. (2)
- Same wavelength/ frequency
* Constant phase relationship/ phase difference
What surrounds optical fibres.? (1)
Cladding
State and explain one advantage associated with a smaller diameter core. (2)
(Any two)
Less light lost/ less multipath dispersion/ better quality signal/ better probability of TIR/ less refraction out of the core
What is the point of maximum displacement called on a stationary wave? (1)
Antinode
Explain why it is important to correctly align the aerial of a TV aerial in order to receive the strongest signal. (2)
- Transmitted radio waves polarised
* Aerials must be aligned in same plane as polarised waves
State and explain one reason why an optical fibre is made as narrow as possible. (2)
- To reduce multipath dispersion
* Which would cause light to arrive at different times/ merge adjacent puzzles
State one application of optical fibres and explain how this has benefited society. (2)
Application - endoscope
Benefit - improved medical diagnosis
Application - communications
Benefit - improve data transmission
How do you increase the fundamental frequency. (1)
Decrease the length/ increase tension/ tighten string
What did Young’s double slit experiment suggest about the nature of light. (1)
Showed light was a wave
State what is meant by monochromatic. (1)
Single wavelength (frequency)
State what is meant by coherent. (1)
Wave source has constant phase difference
State one safety precaution that should be taken when using a laser. (1)
Do not look into laser/ laser safety goggles/ don’t point laser at others
A laser is replaced by another laser emitting visible light with a shorter wavelength. State and explain how this will affect the spacing of the maxima on the screen. (2)
- Maxima closer together
* Spacing is proportional to wavelength as D and s are constant therefore as λ decreases maxima width decreases
Define the amplitude of a wave. (1)
Maximum displacement from equilibrium
Other than electromagnetic radiation, give one example of a wave that is transverse. (1)
Rope/ water ripples/ secondary S waves
State one difference between a transverse wave and longitudinal wave. (1)
(Any one)
• transverse’s oscillations perpendicular to energy
• transverse can be polarised
• longitudinal require a medium
State one application of a polarising filter and give a reason for its use. (2)
- • Polaroid glasses - reduce glare
- • Camera - reduce glare
- • Microscopes - to identify minerals
- • 3D glasses - enhance viewing experience
Describe how the pattern of a single slit light intensity graph would change if light of a longer wavelength was used. (1)
Maxima further apart
State two ways in which the appearance of the fringes would change if the slit was made narrower. (2)
- Wider separation
* Lower intensity
explain why total internal reflection doesn’t occur when a ray travels from water to glass. (1)
TIR only when ray travels from higher n to lower n
