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Physics > Waves > Flashcards

Waves Flashcards

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AP® Physics flashcards Physics 101 flashcards
1
Q

What are the two types of waves?

A

Transverse and longitudinal.

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2
Q

What do waves transfer and what do they not transfer?

A

They transfer energy and not matter.

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3
Q

Transverse wave.

A

Oscillations are perpendicular to the direction of the energy transfer. This can be demonstrated by a slinky spring up and down vertically-waves move horizontally. Ex water wave.

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4
Q

Longitudinal wave.

A

Oscillations are parallel to the direction of energy transfer.
This can be demonstrated by a moving slinky spring moving back and forward horizontally-waves also move horizontally.
Ex sound waves.

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5
Q

When waves reach a boundary between one medium and another what can they be?

A

Reflected, refracted, transmitted and absorbed.

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6
Q

What does the direction of refraction depend on?

A

-The angle at which the waves hit the boundary.
-The materials involved.

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7
Q

What is the refractive index?

A

For light rays the way in which a material affects refraction its called refractive index.

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8
Q

When light travels:

A

-From a material with a low refractive index to a highe one it bends towards the normal.
-From a material with a high refractive index to one with a lower refractive index, it bends away from the normal.

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9
Q

When a light wave enters, at an angle, a medium in which it travels slower:

A

-The first part of the light wave to enter the medium slows down.
-The rest of the wave continues at a higher speed.
-This causes the wave to change direction, towards the normal.

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10
Q

(RP) Investigate reflection and refraction.

A

1) Set up the equipment (lightbox, angles, normal and glass block).
2)Draw around the semi-circular block.
3) Mark the position of the light ray at the start at the end and where it enters/exits the block.
4) Remove the block and connect lines to show the light ray.
5) Add the normal and angles.
6) Repeat on a new paper for different angles.
7) Repeat with different materials.

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11
Q

Variables of RP investigate reflection and refraction.

A

IV= Angle of incidence.
DV = Angle of refraction.
CV= Material of block.

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12
Q

(RP) Identify the suitability of apparatus to measure the frequency, wavelength, and speed of waves in a ripple tank.

A

1) Time how long it takes one wave to travel the length of a tank. Use speed=Distance/time.
2) To find the frequency count the number of waves passing a fixed point in 10 seconds then divide by 10 to find 1 wave.
3) Estimate the wavelength by using s ruler to measure peal to peak distance as the waves travel
4) Use a stroboscope to make the same measurements and compare.

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13
Q

Because all waves obey the wave equation the speed and wavelength are directly proportional:

A

-Doubling the speed, doubles the wavelength.
-Halving the speed, halves the wavelength.

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14
Q

What is the normal hearing range for a human?

A

20Hz to 20KHz

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15
Q

What is the range of frequencies converted dependent on?

A

It is dependent on the structure of the object. Within the ear, sound waves cause the ear drum and other structures to vibrate and it is this vibration that is heard as a sound. Limited range of conversion limits humans hearing.

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16
Q

Are electromagnetic waves transverse or longitudinal?

A

Transverse.

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17
Q

Radio waves, microwaves and infrared waves. (uses and explanations).

A

Radio- TV, radio. Explanation- Low energy waves, not harmful.
Microwaves-Stelite communications, cooking food. Explanation- Travel in straight lines. Ideal for transmitting signals in orbit and back down to the receivers.
Infrared- Electrical heaters, infrared cameras. Explantion- Heater glows red as electricity flows through. Transmits infrared energy that’s absorbed by the food and converted back to food.

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18
Q

Visible light, ultraviolet waves. (uses and explanations).

A

Visible light-Fibre optic communications. Explantion-It travels down optical fibres from one end to the other without being lost.
UV Waves- Efficient light bulbs, sunbeds. Explantion-In light bulbs, UV waves are produced by gas in the bulb when excited by electric current. UV waves are absorbed by coating on the light bulb which fluoresces giving visible light.

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19
Q

X-rays and Gamma rays. (Uses and explanation).

A

X-ray-Medical imaging/treatments. Explantion-Can penetrate soft tissue no bones. Phtotgraphic plate behind will shadow where bones are.
Gamma rays-Sterlisng food and treatment of tumours.
Explantion-Most energetic. Can be used to destroy bacteria and tumours.

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20
Q

(RP) Investigate how the amount of infrared radiation absorbed/radiated by a surface depends on the nature of the surface.

A

1) Take 4 boiling tubes each painted a different colour.
2) Pour hot water into each tube.
3) Measure and record the start temp of each tube.
4) Measure temp of each tube every minute for 10 minutes..
5) The tube that cools the quickest emits infrared energy the quickest.

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21
Q

What are the variables for the RP: investigate the amount of infrared radiation..

A

IV=Colour of the boiling tube.
DV=The temperature.
CV=Volume of water, start temp and environmental conditions.

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22
Q

Radio signals.

A

-Can be caused by oscillations in electric circuits, ie an AC.
-Frequency of the radio wave produced matches the frequency of the electrical oscillation. This is how a signal is produced.
-When a wave is absorbed by a conductor they may create an AC with the same frequency as the wave, this is how the signal is received.
-When this oscillation is induced in an electrical circuit it creates an electrical signal that matches the wave.

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23
Q

Hazards of EM waves.

A

Ultraviolet waves can cause the skin to age prematurely and increase the risk of skin cancer.
-X-rays and gamma rays are ionising radiation-they can damage cells by ionising atoms and if absorbed by the nucleus of the cell can cause gene mutations and cancer.

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24
Q

A perfect black body:

A

-absorbs all of the infrared radiation incident on it.
-does not reflect or transmit any infrared radiation.
It is the best possible emitter.

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25
Q

The temperature of an object (or body) determines:

A

-the rate at which it emits radiation.
-the wavelength of the radiation it emits.

26
Q

What is the temperature of an object related to?

A

It’s related to the balance between radiation absorbed and radiation emitted.

27
Q

Why will the ground increase in temperature on a sunny day?

A

Because it absorbs radiation from the sun faster than it emits radiation. As temp increases so will the rate at which it emits radiation. Eventually, the rate of emission is equal to the rate of absorption and the ground will be a constant temperature.

28
Q

What does the temperature of the earth depend on?

A

-How much energy it receives from the sun.
-How much energy is reflected back Into space.
-How much energy is emitted into space.
The earth’s atmosphere also affects how much of the radiation emitted form the surface escapes into space.

29
Q

Longitudinal waves show areas of?

A

Compression and rarefraction.

30
Q

Amplitude of a wave.

A

The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position.

31
Q

Wavelength of a wave.

A

The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave.

32
Q

Frequency of a wave.

A

The frequency of a wave is the number of waves passing a point each second.

33
Q

Period equation.

A

period = 1
frequency

34
Q

Wave speed equation.

A

wave speed = frequency × wavelength

35
Q

What are the two types of lens?

A

Concave and convex.

36
Q

Convex lens.

A

It is wider in the middle than at the edges.
-Parallel rays of light entering a convex lens are brought to a focus at the principal focus or focal print.
-Because parallel rays of light entering a convex lens converge and are called converging lenses

37
Q

What is the focal length?

A

The distance from the lens to the principal focus is the focal length.

38
Q

Concave lens.

A

-Parallel rays of light entering a concave lens spread out.
-This makes the rays appear to have come from the principal focus on the same side of the lens they originated from. The rays diverge and are called diverging lenses.

39
Q

How does a lens form an image?

A

By reflecting light.

40
Q

What images do concaves and convex lenses produce?

A

Concave-Virual images only.
Convex- Real and virtual images.

41
Q

Real image/Virtual image.

A

A real image is on the opposite of the lens to the object and can be projected on the screen.
A virtual Image is on the same side as the object and cam only be seen by looking through lens.

42
Q

How do you draw a ray diagram?

A

-Draw the principal axis- Horizontal that runs straight through the lens.
-Use the correct lens symbol.
-Mark the principal foci on either side of the lens by drawing a dot on the axis and label it F.
-Mark the position of the object as an arrow standing on the axis.
-Once the diagram is laid out draw the light rays.

43
Q

How to draw a convex lens?

A

1) Draw a horizontal line that runs straight from the top of the object to the lens.
2) Draw a 2nd line from where the first line meets the lens down through the principal focus on the far side of the lens.
3) Draw a 3rd line from the top of the object running diagonally through the middle of the lens and out on the other side.
4) If the lines meet on the opposite it’s a real image. Draw the image upside down.

44
Q

How to draw a concave lens?

A

-Draw a horizontal line that runs from the top of the object to the lens.
-Draw a dotted line from the principal focus on the same side as the object to the point where the first line meets the lens. Continue this line as solid through the lens.
-Draw a third line from the top of the object running diagonally through the lens.
-When the dotted line meets the third line it makes the top of the image, this will be virtual and the right way up.
Draw a vertical arrow where the lines meet.

45
Q

What does visible light describe?

A

It describes the electromagnetic waves that can be detected by the human eye.

46
Q

What is specular reflection?

A

Reflection by a smooth surface in a single direction is called specular reflection.

47
Q

What does transparent, translucent and opaque mean?

A

Transparent- Transmits light coherently (rays don’t get jumbled) so objects can be seen clearly.
Translucent- Objects cannot be seen clearly through them.
Opaque-They either reflect or absorb all light incident on them so no light passes through.

48
Q

What colour will the object appear if all wavelengths are reflected equally?

A

White.

49
Q

What colour will the object be if all wavelengths are absorbed?

A

Black.

50
Q

If the object is a different colour to the filter then what would happen?

A

-A red and blue striped object seen through a red filter will appear red and black. The blue light will not pass.
-The same object seen through a green filter will be completely black. No red or blue can pass through the filter.

51
Q

What happens when an ultrasonic wave meets a boundary between 2 different media?

A

It is partially reflected.

52
Q

How is it possible to determine how far away a boundary is?

A

By measuring the time taken for reflected ultrasonic waves to return to a detector.

53
Q

How is ultrasound used in the industry?

A

It could detect defects without the need to cut into materials. These defects could be manufacturing faults (cracks/bubbles) or damage (corrosion).

54
Q

What is echo sounding?

A

The use of ultrasonic waves for detecting objects in deep water and, measuring the depth of water. It involves sending an ultrasound pulse into the water which is then reflected back when it hits a surface. The time between the pulse and reflection being detected is used to calculate the distance travelled by the sound wave using: Distance-Speed*time.
Then divide by 2 to find the depth of the water.

55
Q

What are the two types of seismic waves?

A

P-waves (primary)
S-waves (secondary).

56
Q

P-waves.

A

-Longitudinal.
-Travel at the speed of sound and are twice as fast as S-waves.
-Travel at different speeds through solids and liquids.

57
Q

S-waves.

A

-Transverse waves.
-Cannot travel through liquids.

58
Q

What happens during an earthquake?

A

-Seismic waves travel outwards from the earthquake and can travel all over the world.
-Seismic waves travel in a curved path due to the earth’s increase in density with depth.
-Dectors placed around the earth measure when/where the wave comes from.

59
Q

S-waves shadow zones.

A

-Not able to travel through the liquid outer core of the earth.
-Results in a large shadow zone on the opposite side of the earth to where the earthquake originated.
-This zone provides evidence of the size of the earth’s core.

60
Q

P-wave shadow zone.

A

-Can travel through the liquid in the outer core.
-However, they are refracted at the boundary between the semi-solid mantle and the liquid outer core.
-They refract again at the boundary between the liquid outer core and solid inner core.
-Refractions result in p-wave shadow zones.
-Study of these shadows is used to determine the size/composition of the inner/outer core.

Physics (9 decks)

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