Waves, Reflection, Refraction, Lenses Flashcards by Priyan Yaddehige

Wave

An oscillation(vibration) that moves through a medium

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Waves transfer… and don’t transfer…

Energy, Matter

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What direction is the oscillations of a transverse wave?

Perpendicular to the direction of the energy transfer of the wave

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What direction is the oscillations of a longitudinal wave?

Parallel to the direction of the energy transfer of the wave

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Compressions

Areas where particles are clumped together

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Rarefactions

Areas where particles are low and spaced out

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Features of a transverse wave(6)

-Peak
-Trough
-Amplitude (max. displacement)
-Wavelength
-Frequency
If you put an x on the right-farthest end of the x-axis, it indicates that space is being measured not time
(look at pic 1)

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Features of a longitudinal wave

-Compression
-Rarefaction
-Wavelength
(look at pic 2)

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Wavelength

Distance between same point on 2 adjacent wavelengths

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Wave length symbol and unit of measurement

λ , metres

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Time period symbol and unit of measurement

T , seconds

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Both Wavespeed formulae, symbol and unit of measurement

Wave length/ Time period or Frequency * Wavelength, v , m/s

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Frequency formula, symbol and unit of measurement

1/ Time period, f, Hz

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In a transverse wave graph, if the x axis is… instead of space, then what was the wavelength is now the…

Time, Time period (look at pic 3)

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What does frequency mean?

How many waves pass per second

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At the boundary of transmission, several things may happen to the wave(4):

-Reflection
-Refraction
-Absorption
-Transmission

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The normal is… to the surface

perpendicular

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The law of reflection

Angle of Incidence = Angle of Reflection

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The angle of incidence is the angle between the light ray and the…

normal

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Diffuse reflection

When light is reflected on an uneven surface(an irregularly reflecting surface) and as a result the light reflects at various angles and you won’t be able to ‘see a reflection’ (look at pic 4)

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Specular reflection

The opposite of diffuse reflection, when the light reflects on an even surface and a visible image can be seen (look at pic 4)

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Example of comparison between diffuse and specular reflection

A raging river vs a still lake

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Refraction

The change in direction of a wave when passing between 2 transparent materials

For refraction, the angle between incident ray and the surface is the same as…

the angle between the emergent ray and the normal (look at pic 5)

What are the 3 rays in refraction?

Incident ray, refracted ray and emergent ray (look at pic 5)

What state of matter does sound travel best in?

Solids

What are the ear parts in order?(6)

-Pinna -Auditory Canal -Eardrum -Ossicles -Cochlea -Auditory nerve (look at pic 6)

Function of Pinna

Collects the sound waves

Function of Auditory Canal

Wave travels along the auditory canal

Function of Eardrum

Vibrates because of the waves

Function of Ossicles

Amplifies vibration

Function of Cochlea

Turns vibration into an electrical signal

Function of Auditory Nerve

Carries signal to the brain

How can speed of sound be measures in an experiment?

By hitting 2 wooden blocks together from a distance, and calculate the difference in time between seeing and hearing it

What formula does the wood block experiment use?

v = s/t

What would you need for the wood block experiment?(4)

-Objects that would make a loud noise -A stopwatch -A meter wheel -2 people

What could be sources of error in the wood block experiment?(3)

-Hard to see -Reaction time -Loud background noise

How can error be reduced in the wood block experiment?

Not so close so they won't actually have time to react to it, but not so far that they will struggle to see or hear it; find the right distance beforehand

Ultrasound

Sound with a frequency higher than 20kHz

When ultrasound waves meet a boundary between two different media, they get...

Partially reflected (also look at pic 7)

Ultrasound uses(5)

-Foetal scans (safe, see reflections off soft tissues) -Sonar (detect underwater objects) -Treatment (kidney stones broken by high frequency) -Cleaning/ hygiene (High frequency can break up dirt i.e. electric toothbrushes) -Medical diagnosis

Seismic waves

Waves produced by an earthquake

2 Types of seismic waves

Surface waves and body waves

2 Types of body waves

Primary waves (p-waves) Secondary waves (s-waves)

Are p-waves transverse or longitudinal?

longitudinal

Are s-waves transverse or longitudinal?

transverse

Can p-waves pass through solids and liquids?

Yes

Can s-waves pass through solids and liquids?

No, only solids

For the earth diagram (pic 8), what does the fact that the p-wave refracts tell us about the earths core as you go deeper?

The density changes, meaning the presence of a boundary

For the earth diagram (pic 8), how can we tell that the outer core is at least partially made from liquid material?

p-waves can travel through it, but s-waves can't

Will p-waves travel through: Mantle? Outer core? Inner core?

-Will pass through mantle -Will pass through outer core -Will pass through inner core

Will s-waves travel through: Mantle? Outer core? Inner core?

-Will pass through mantle -Can't pass through outer core -Can't pass through inner core since it can't even reach it if it can't pass through the outer core

What are the 2 lens types?

Convex and concave (look at pic 9)

Why does looking at an image through a convex turn it upside down?

The curved surface of the mirror causes the light to bend at an angle which will cause all the light rays refracting through to converge (the principal focus), and then continue going further in a way where the highest light ray is at the bottom and vice versa. (look at pic 10 and it'll make more sense)

Check out pic 11 and 12 as well

Add anything if there was any facts missing