Flashcards
Waves
Cards in this deck (27)
- 1WavesPhysics 1b 2.1 - 2.5
- 2What is the amplitude of the wave?The displacement from the crest to the rest position.
(Labelled A and B on the diagram) - 3What is the wavelength of a wave?The length of a full cycle of a wave, eg. from crest to crest.
(Labelled as lambda on the diagram)
- 4What is the frequency of a wave?Number of complete waves passing a certain point per second OR the number of waves produced by a source each second. Frequency is measured in Hz - 1Hz is 1 wave per second.
- 5Give four examples of transverse waves.1) Light and other EM waves
2) Ripples in water
3) Waves on strings
4) A slinky wiggled up and down - 6Define 'transverse wave'.The vibrations are perpendicular to the direction of energy transfer of the wave.
- 7Give three examples of longitudinal waves.1) Sound waves and ultrasound
2) Shock waves, eg. seismic waves
3) A slinky when you push the end - 8Define 'longitudinal wave'.The vibrations are parallel to the direction of energy transfer of the wave.
- 9What is the equation for wave speed?speed (m/s) = frequency (Hz) x wavelength
Hence, v = f x λ
f = v / λ
λ = v / f - 10What happens when a wave meets an obstacle?Their direction of travel changes, this can happen by reflection, or by refraction or diffraction.
- 11What is reflection?This allows us to see, light bounces off of an object and into our eyes. When light travelling in the same direction reflects from an uneven surface such as a piece of paper, the light reflects off at different angles. When light travelling in the same direction reflects from an even surface such as a mirror, then it's all reflected at the same angle and you get a clear reflection.
- 12What is the law of reflection?angle of incidence = angle of reflection
- 13Describe the ray diagram for a reflected ray against the shiny side of a mirror.
- 14What is the normal on a ray diagram?An imaginary line that's perpendicular to the surface at the point of incidence.
- 15Describe the first stage of drawing a ray diagram for an image in a plane mirror.1) Draw the virtual image - this should be the same size and distance from the mirror as the actual object.
- 16Describe the second stage of drawing a ray diagram for an image in a plane mirror.2) Draw a reflected ray going from the top of the virtual image to the top of the eye. Draw a bold line between the mirror and the eye, but a dotted line between the virtual image on the mirror.
- 17Describe the third stage of drawing a ray diagram for an image in a plane mirror.3) Draw the incident ray going from the top of the object to the mirror, the incident and reflected rays follow the law of reflection - but you don't actually have to measure any angles. Draw the ray from the object to the point on the mirror where the reflect ray falls.
- 18Describe the fourth stage of drawing a ray diagram for an image in a plane mirror.Repeat steps two and three from the bottom of the eye to the bottom of the virtual object.
- 19State the properties of a reflected image.1) The image is the same size as the object.
2) Equal distance between the mirror and object as there is between the mirror and image.
3) Virtual and upright.
4) Laterally inverted - left and right have swapped. - 20What does it mean when a wave is said to have been refracted?They go through a different medium but change direction.
- 21What does it mean when an object is said to have been diffracted?The waves have 'bent' around an object, causing the waves to spread out.
- 22What does the amount of diffraction depend upon?The size of the gap relative to the wavelength of the wave. The narrower the gap, or the longer the wavelength, the more the waves spread out.
- 23What is meant by a narrow gap?One that is the same order of magnitude as the wavelength of the wave - ie. they are about the same size.
- 24Describe the wave diagrams for diffraction.
- 25In what circumstances would light be refracted?When a ray passes between a less dense material to a denser material at an angle. If the wave hits the boundary between the two mediums perpendicularly, then it continues in the same direction.
- 26What happens if the light wave is travelling along the normal?The angle of incidence will be zero, therefore the light changes speed but will NOT be refracted.
- 27Describe a refraction diagram.
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- Flashcards on Waves, created by Lauren Adams on 13/05/2016.
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- Lauren Adams
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