Waves Flashcards
Describe:
Transverse Waves
Perpendicular oscillations
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Describe:
Longitudinal Waves
Parallel oscillations
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Equation:
Wave Speed
v = fλ
Wave speed = Frequency x Wavelegth
Required Practical:
Water Ripples
1) Using a signal generator, attached to the dipper of a ripple tank you can create water waves at a set frequency
2) Use a lamp to see wave crests on a screen below the tank. Make sure the size of the waves’ shadows are the same size as the waves
3) The distance between each shadow line is equal to one wavelength. Measure the distance between shadow lines that are 10 wavelengths apart, then divide this distance by 10 to find the average wavelength
4) Use v = λf to calculatethe speed of the waves
Required Practical:
Waves on String
1) Set up a string connected to a vibration transducer one one end, and some masses over a pulley on the other. Turn on the signal generator and the string will begin to vibrate
2) Adjust the frequency of the sugnal generator until there’s a clear wave on the string. The frequency you need will depend on the length of the string between the pulley and the transducer, and the masses you’ve used
3) You need the measure the wavelength of the waves. The best way to do this accurately is to measure around 4 half-wavelengths, divide them to find the average half-wavelength and then double to get a full wavelength
4) The frequency of the wave is whatever the signal generator is set to
5) You can find the wave speed using v = λf
Describe:
How waves interact with boundaries
Waves can be absorbed by the material
Waves can be transmitted - often refraction
Waves can be reflected
Describe:
Reflection Rule
Angle of Incidence = Angle of Reflection
Describe:
Specular Reflection
Reflected in a single direction by a smooth surface
Describe:
Diffuse Reflection
Reflected by a rough surface
Reflected rays are scattered in lots of directions
Describe:
Electromagnetic Spectrum
Radio Waves
Microwaves
Infrared
Visible Light
Ultraviolet
X-Rays
Gamma Rays
Describe:
What happens as you go down EM Spectrum
Frequency increases
Wavelength decreases
Define:
Refraction
When a wave crosses a boundary between materials at an angle and changes direction as the wave speeds up or slows down.
Required Practical:
Investigating Light (Refraction)
1) Place a transparent rectangular block on a piece of paper and trace around it. Use a ray box or a laser to shine a ray at the middle of one side of the block
2) Trace the incident ray and mark where the light ray emerges on the other side of the block. Remove the block and, with a straight line, join up the incident ray and the emerging point to show the path of the refracted ray through the block
3) Draw the normal at the point where the light ray entered the block. Use a protractor to measure the angle between the incident ray and the normal
4) Repeat this experiment using rectangular blocks made from different materials, keeping the incident ray the same throughout
Required Practical:
Investigating Light (Reflection)
1) Take a piece of paper and draw a straight line across it. Place an object (such as a mirror) so one of its sides lines up with this line
2) Shine a ray of light at the object’s surface and trace the incoming and reflected light beams
3) Draw the normal at the point where the ray hits the object. Use a protractor to measure the angle of incidence and the angle of reflection and record these values in a table. Also make a note of the width and brightness of the reflected light ray
4) Repeat this experiment for a range of objects
Define:
Radiation Dose
Measured in Sieverts
Measure of the risk of harm from the body being exposed to radiation
Describe:
Convex Lenses
↕
Causes rays of light to converge at the principal focus
Principal focus is where rays meet
Describe:
Concave Lenses
v
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Causes rays of light to diverge
Principal focus is the point where rays hitting the lens come from
Define:
Three Rules for Convex Lens Refraction
1) An incident ray parallel to the axis refracts through the lens and passes through the principal focus on the other side
2) An incident ray passing through the principal focus refracts through the lens and travels parallel to the axis
3) An incident ray passing through the centre of the lens carries on in the same direction
Define:
Three Rules for Concave Lens Refraction
1) An incident ray parallel to the axis refracts through the lens, and travels in line with the principal focus
2) An incident ray passing through the lens towards the principal focus refracts through the lens and travels parallel to the axis
3) An incident ray passing through the centre of the lens carries on in the same direction
Define:
Real Image
Where light from an object comes together to form an image on a ‘screen’
Define:
Virtual Image
When the rays are diverging, so the light from the object appears to be coming from a completely different place
Equation:
Magnification
Magnification = Image Height / Object Height
Describe:
Visible Light Spectrum
Red
Orange
Yellow
Green
Blue
Indigo
Violet
Define:
Opaque
Does not transmit light
Absorbs some light, Reflects some light
