P1.5 Flashcards

1
Q

What does red shift show?

A

That a star is moving away from Earth

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2
Q

What does blue shift show?

A

That a star is moving towards Earth

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3
Q

Why does a star moving away look red?

A

Because the waves it produces behind it are stretched out and have a long wavelength, which makes them appear red

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4
Q

What does a star moving towards earth look blue?

A

Because the waves it produces infront of it are compressed and have a short wavelength, which makes them appear blue

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5
Q

What does red galaxies in the sky prove?

A

That at some point in the past the galaxies must’ve been together, and the entire universe is expanding

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6
Q

What is cosmic microwave background radiation?

A

A type of radiation which is believed to have been present shortly after the Big Bang

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7
Q

What is the Big Bang theory?

A

It states that the universe started from a precise small point billions of years ago and has been expanding since

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8
Q

What led to the scientific community accepting the Big Bang theory?

A

The discovery of CMBR in the 1960s

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9
Q

When we look at the sun why are some frequencies of light not seen?

A

Because they’re absorbed by hydrogen and helium

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10
Q

A more distant galaxy is doing what?

A

Moving away faster

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11
Q

What is amplitude?

A

The peak of movement of the sound wave from its rest point

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12
Q

What does the amplitude affect?

A

The loudness of the sound

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13
Q

What type of waves does sound travel as?

A

Longitudinal waves

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14
Q

How are sound waves produced?

A

By something vibrating

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15
Q

What are some properties of sound waves?

A

~ Can’t travel through a vacuum
~ Reflect off hard surfaces to produce echoes
~ Refracted when it passes into a different medium or substance
~ Diffracted around buildings or land masses

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16
Q

What is the frequency of a sound wave?

A

The number of vibrations produced in one second

17
Q

How does frequency affect sound?

A

It affects the pitch

18
Q

What is frequency measured in?

A

Hertz (Hz)

19
Q

What is a use of the different waves in the electromagnetic spectrum?

A

Radio waves - TV signals
Microwaves - Bluetooth devices / satellite communication
Infrared rays - Remote controls
Visible light - Photography
Ultraviolet rays - Sunbeds
X-Rays - Producing shadow pictures of bones
Gamma rays - Killing cancerous cells

20
Q

What are risks associated with ultraviolet rats, X-Rays and gamma rays?

A

High doses can kill (cancerous) cells and low doses can cause cancer

21
Q

What are risks associated with radio waves?

A

High exposure can increase body temperature, leading to tissue damage, especially to the eyes

22
Q

What are risks associated with microwaves?

A

They’re absorbed by water in the cells causing a release of heat and damaging or killing cells

23
Q

What are risks associated with infrared rays?

A

Absorbed by skin, can cause burns

24
Q

What is the wave speed?

A

How quickly the energy moves, m/s

25
Q

What’s an example of a transverse wave?

A

Waves in water

26
Q

What are the oscillations like in a transverse wave?

A

The oscillations in a transverse wave are perpendicular to the direction of energy transfer

27
Q

What are the oscillations like in a longitudinal wave?

A

The oscillations in a longitudinal wave are parallel to the direction of energy transfer

28
Q

What are the points on a longitudinal wave called when the lines are bunched together?

A

Compressions

29
Q

What are the points on a longitudinal wave called when the lines are spread out?

A

Rarefactions

30
Q

What is an image produced by a mirror like?

A

~ Virtual
~ Upright
~ Laterally inverted

31
Q

When is diffraction greatest?

A

When the gap is the same width as the wavelength

32
Q

What type of waves are electromagnetic waves?

A

Transverse waves

33
Q

What are properties of electromagnetic waves?

A

~ Can travel through a vacuum
~ Travel at the same speed though a vacuum
~ Can be reflected and refracted

34
Q

What wave has the highest frequency and the shortest wavelength?

A

Gamma rays

35
Q

What wave has the lowest frequency and the longest wavelength?

A

Radio waves

36
Q

How is the visible light spectrum produced?

A

White light is made of different colours which are refracted by different amounts as they pass through a prism - red light is refracted the least and violet is refracted the most