Astro

Question 1

1. How did Thomas Young prove light was a wave? (use relevant terms like diffraction, Refraction, interference, crests, troughs)

Answer 1

Young set up a screen with a small opening, called a slit, allowing light to pass through. Beyond this slit, he placed a barrier with two closely spaced parallel slits, referred to as the double-slit. This setup allowed light to pass through both slits and then interfere with itself on a screen placed further away.
Interference: Light passing through the double slits would diffract, spreading out into a pattern of alternating bright and dark bands on the screen.
Crests and Troughs: When two waves meet in phase (with their crests and troughs aligning), they reinforce each other, producing a brighter spot. When they meet out of phase (crest of one wave aligns with the trough of the other), they cancel each other out, creating a dark spot.
Pattern Formation: Young observed that the pattern of bright and dark bands on the screen was consistent with interference patterns seen in waves such as water waves.
Diffraction and Refraction: The diffraction of light through the slits and its subsequent interference with itself on the screen demonstrated its wave-like behavior. Additionally, the bending of light as it passed through the slits (refraction) further supported the wave nature of light.

Question 2

2. List the various forms of electromagnetic radiation from the highest energy to the lowest energy

Answer 2

gamma. - (highest energy, shortest wavelength))
x rays,
ultraviolet
visible, - (in the middle of the EM spectrum, what we see)
infrared,
microwaves,
radio - (lowest energy, longest wavelength)

Question 3

List the various forms of electromagnetic radiation from the longest wavelengths to the shortest.

Answer 3

Radio, Microwaves, Infrared, Visible, Ultraviolet, xrays, gamma.

Question 4

What does it mean to say frequency and wavelength are inversely proportional?

Answer 4

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On the other hand, frequency and wavelength are inversely proportional; as one increases the other decreases and vice versa.

Question 5

5. At what speed do electromagnetic waves move?

Answer 5

Electromagnetic waves move in a vacuum at the speed of of light, i.e., at approximately 300,000 km/s

Question 6

How are electromagnetic waves produced?

Answer 6

Electromagnetic (EM) waves are created when an atomic particle, such as an electron or proton, oscillates (jiggles around). This oscillation (vibration) interacts with the electric field (which invisibly pervades the entire universe), and produces an electric wave (a disturbance in the feld). The electric wave, moving away from the particle, then produces a magnetic wave (in a direction away from the particle). The magnetic wave in turn produces an electric wave… on and on…creating one another, forever, carrying the energy away from the source (the original oscillating particle)

Question 7

Our atmosphere is opaque to certain EM waves. Which ones

Answer 7

Gamma, X-rays, and most Ultraviolet.

Question 8

8. The Earth’s atmosphere is transparent to certain waves. Which ones”

Answer 8

s” The atmosphere is transparent to visible light, most radio waves, and some infrared light

Question 9

What forms of EM radiation penetrate our atmosphere and make it to the
Earths’ surface?

Answer 9

EM radiation, coming to Earth from space, will first encounter our atmosphere

Question 10

How did Roemer determine the approximate speed of light? Why was it not the exact value

Answer 10

Ole Roemer, a Danish astronomer, was the first to attempt to measure the speed of light Here is how he did it. He knew that Io’s orbital period is 42 hours and 27 minutes. So, every 42 hours and 27 minutes Roemer would observe, from position A below, that Io would disappear behind Jupiter - right on time, every time. However, when he observed Io from position B, 6 1/2 months later, when the Earth was on the opposite side of the Sun, he noticed that Io disappeared 22 minutes later, This meant that it was taking the light from Io 22 extra minutes 1320 seconds) to travel across Earth’s orbit. The accuracy of Rømer’s measurements depended on the precision of his observations of the eclipses of Io, which were subject to various sources of error such as atmospheric distortion and instrumental limitations.
• Orbital Dynamics: The moons of Jupiter do not have perfectly circular orbits, and their motion is influenced by gravitational interactions with other celestial bodies. These factors could have introduced complexities into Rømer’s calculations.

Question 11

. Discuss the differences between a continuous spectrum, an absorption spectrum and an emission spectrum

Answer 11

• . Continuous meaning all colors (wavelengths are present). An absorption line is a dark line. absorption lines are caused by the atoms in the hydrogen gas absorbing specific wavelengths of light from the light beam.
The emission lines (on top above) are caused by the hydrogen gas emitting (giving back) the wavelengths it absorbed.

Question 12

12. What are Fraunhofer lines? I

Answer 12

In 1814, the German physicist Joseph Fraunhofer observed that the spectrum of the Sun showed dark lines crossing a continuous band of colors (these are the absorption lines).

Question 13

13. How did Kirchoff determine what elements are present in the Sun?

Answer 13

Kirchhoff took the gigantic leap of correlating the dark spectral lines Fraunhofer observed in the Sun’s spectrum, with the emission lines observed by various heated chemical substances in the laboratory. He noticed that the positions of the spectral lines of certain chemical elements exactly matched the positions of certain lines that Fraunhofer observed on the Sun.
In this manner Kirchhoff (1) demonstrated the existence, in the Sun, of many chemical elements found on Earth.

Question 14

If the Sun is so hot, and hot gases give off emission lines, why does the Sun (and all stars) display absorption lines? In other words, how are the absorption lines produced on the Sun and stars?

Answer 14

absorption lines in the spectrum of the Sun and stars are produced when light emitted from their interiors passes through cooler outer layers containing atoms of various elements. These atoms selectively absorb specific wavelengths of light, resulting in dark lines in the spectrum observed from Earth.

Question 15

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15. What is the nanometer (nm) wavelength range of visible light (google i

Answer 15

• The visible light spectrum ranges from approximately 400 nanometers (nm) to 700 nanometers (nm) in wavelength.

Question 16

What are the three basic particles in an atom.

Answer 16

. Protons, Neutrons and electrons

Question 17

7. Within an atom, an electron always wants to be in the ________ state, as close to

Answer 17

Electrons always want to be in their ground state, as close to the nucleus as possible.

Question 18

Big Question: How are spectral lines formed?

Answer 18

• When electrons move from a higher energy level to a lower one, photons are emitted, and an emission line can be seen in the spectrum.

Question 19

19. Why do spectral lines have different colors? S

Answer 19

? Spectral lines have different colors because they correspond to different wavelengths of light. The color of light is determined by its wavelength, with shorter wavelengths corresponding to colors like violet and blue, and longer wavelengths corresponding to colors like red and orange. Therefore, spectral lines with shorter wavelengths appear blue or violet, while those with longer wavelengths appear red or orange.

Question 20

20. What is the primary reason why stars have different spectra?

Answer 20

The primary reason why stars have different spectra is because stars have different temperatures.

Question 21

What is the primary element that stars are made from

Answer 21

Hydrogen. It has 90%

Question 22

2. Why are the four spectral lines for hydrogen not detected in very hot, or cool stars
   but only in intermediate A-type stars ?

Answer 22

? Too Cool - In cooler stars with LOW surface temperatures, the sluggish atoms and molecules in the atmosphere do not have enough energy to move around as fast as those in a hotter gas. There will be fewer energetic collision between atoms to catapult electrons into excited states, so essentially all the hydrogen atoms will have their electrons in the ground state. Even if there are many hydrogen atoms, there will be no tell-tale absorption features. These are G, K and M type stars above
Too Hot - On the other hand, In really hot stars with HIGH surface temperatures, the atoms in the atmosphere fly around very quickly. There are many energetic collisions, but a large fraction of the hydrogen atoms are ionized, which means, they have lost their electrons entirely, so they have no chance of producing absorption lines. These are O types stars above
Just right - For stars with just the right surface temperature (A type stars) such that collisions continuously populate the first excited state with electrons, there will be lots of photons caught that excite the electrons to the second excited level, and subsequently higher levels, so there will be strong hydrogen absorption lines

Question 23

23. List the seven spectral types of stars (not including brown dwarfs) from hottest
    To coolest The spectral class assigned to each of these stellar spectra is listed

Answer 23

O, B, A, F, G, K, M (Historically, a mnemonic “Oh-Be-A-Fine-Girl(Guy)-Kiss-Me

Question 24

25. A failed star is known as a__

Answer 24

Brown darf

Question 25

We cannot measure a star’s temperature directly. However, there are two indirect

Answer 25

Besides spectral class, there is another way to determine a star’s temperature, its color (peak wavelength)

Simply, temperature determines the color and peak wavelength.

Peak wavelength and color are two ways of expressing at the same thing - they are related.

Question 26

What is meant by the “peak wavelength” of a star?

Answer 26

The “peak wavelength” of a star refers to the wavelength at which the star emits the most intense radiation, often in the form of electromagnetic radiation such as visible light, infrared, or even ultraviolet, depending on the star’s temperature.

Question 27

28. What is a blackbody distribution curve?

Answer 27

A blackbody is a hypothetical body which absorbs all radiation falling on it, reflecting or transmitting none. It is a hypothetical (not real) object which is a perfect absorber and a perfect emitter of radiation over all wavelengths equally. Blackbodies only emit light when they are heated, and the temperature to which they are heated determines their precise color of light they emit.

Question 28

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29. A star’s color and spectral class is determined by it

Answer 28

Temp

Question 29

Big Question How are color, temperature, wavelength, frequency, and energy
relate

Answer 29

? Color, temperature, wavelength, frequency, and energy are all interconnected through the electromagnetic spectrum and the behavior of electromagnetic radiation:

Question 30

1. List the colors of stars from coolest to hottest.

Answer 30

Red
• Orange
• Yellow
• White
• Blue