1. Prepare your scantron: Setup:
Use
a pencil,
not a pen!
Fill in your name and fill the bubbles under
your name.
LAST NAME FIRST, First name second
Put your 4-digit code instead of “IDENTIFICATION NUMBER”.
--- (The last 4 digits of your OleMiss ID.)
Question # 1: answer A
Question # 2: answer B
Question # 3: answer D
Setup:
Recall reading assignment
Chapter 5 (Light and matter)
pp. 137 – 164
Pass/fail test
Sept. 26, Tomorrow
6:00-7:00 pm
Please take a moment to mute your cell phone!

2. Review questions
coming …

3. This question counts double!
sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 4
Which of the following is not an electromagnetic wave?
A Laser.
B Starlight.
C X-rays.
D Infrared.
E All of the above are electromagnetic waves.
Next question coming …

4. This question counts double!
sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 5
X-rays and light are different because they have …
A different nature: light is a wave, X-rays are radiation.
B different electric charge.
C different energy per second.
D different speed.
E different wavelengths.
Next question coming …

5. This question counts double!
sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 25 27 28 30 29 17 24 19 18 23 20 22 21
Question 6
The main constituents of an atom are:
A Protons, neutrons, and electrons.
B Electrons and a nucleus.
C A nucleus, electrons, protons, and neutrons.
D An atom has no constituents because it is indivisible.
E Photons and electrons.

6. Photons Einstein’s  light comes in chunks (photons)
discovery:  each photon has E=1240/l energy
Red l = 720 nm, E = 1.7 eV
Blue l = 420 nm, E = 3 eV
UV l = 100 nm, E = 12 eV
X-ray l = 1 nm, E = 1200 eV
in electron-volts (eV) in nm’s
Enough to destroy most atoms
Destroys everything if strong

7. Also: white shirts glow in “black light”
In astronomy
Light is produced by:
Light production
• Stars are hot, glowing: thermal radiation
• Charged particles hitting magnetic fields:
synchrotron radiation
M 1(The Crab Nebula)
• Charged particles hitting
gas: fluorescence
• Hot stars’ UV cause
interstellar gas glow: fluorescence
Also: white shirts glow in “black light”
NGC 6369

8. Questions coming …

9. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 7
A proton is the same thing as
A The nucleus of a helium atom.
B A positively charged electron.
C An ionized helium atom.
D The nucleus of a hydrogen atom.
E A hydrogen atom.
Next question coming …

10. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 8
Can a chemical process turn hydrogen into helium?
A Yes, but only at very hot temperature.
B Yes, and that is the process that keeps the Sun hot.
C No, because too much energy is needed to change one nucleus into another.
D No, because a chemical process can turn hydrogen only into oxygen.
Next question coming …

11. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 9
Which of the following is correct about
red and blue light?
A Red light always contains more photons than blue light.
B Red light always contains fewer photons than blue light.
C A blue photon is more energetic than a red photon.
D A blue photon is less energetic than a red photon.
Next question coming …

12. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 10
Which one of the following is
an example of fluorescence?
When substances (gas in astronomy) …
A glow because they reflect the light of a star.
B glow because they are hot.
C glow because they are illuminated by UV light.
D glow because they reflect sunlight.
E glow because electrically charged particles hit magnetic fields.
Next question coming …

13. sec 10 9 11 13 14 8 12 7 2 1 3 4 6 5 15 17 26 25 27 28 30 29 16 24 19 18 23 20 22 21
Question 11
What is thermal radiation?
When substances (gas in astronomy) …
A glow because they reflect the light of a star.
B glow because they are hot.
C glow because they are illuminated by UV light.
D glow because they reflect sunlight.
E glow because electrically charged particles hit magnetic fields.

14. Distinction looses sense (inside stars or planets)
The phases of matter
 Solid
 Liquid (only under pressure
– rarely in astronomy)
 Gas
Phases
Distinction looses sense
under great pressure
(inside stars or planets)
 that matter is “mush”
Hot matter:
T > 1, ,000 K falls apart into atoms (gas )
T > 2, ,000 K atoms are ionized (plasma)
(Note: H and He need much higher
temperature to ionize, T > 10,000 K)

15. What is plasma?  Matter with a lot of ionized atoms.
 Feels magnetic field
Examples: Flame
Lightening bolt
Substance of the stars
The Solar wind
Hot interstellar matter
Notice: hydrogen can be H2, H=HI, H+=HII
helium can be He=HeI, He+=HeII, He++;=HeIII
oxygen can be O2, O=OI, O+= OII, O++=OIII, … , O = OIX.
Ionization and plasma
The substance of
Earth : solid in the crust liquid-like “mush” inside
Jupiter : gas outside gas-like “mush” inside
Sun : plasma gas outside plasma “mush” inside
Interstellar  when gas: H2, H, H+, and other atoms, ions, and molecules
matter  when solid grains: ice and rock

16. Cosmic rays From Deep Space The Solar Wind protons, electrons
Earth’s
atmosphere and magnetic field
absorb them
(dangerous for astronauts)
very energetic protons & nuclei
break up into showers
of many less energetic particles
in the atmosphere.
(always present: causes mutations)

17. Questions coming …

18. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 12
What is the substance of the outer edge of the Sun?
A Solid.
B Liquid.
C (At least partially) ionized gas.
D Molecules.
E A gas of purely neutral hydrogen atoms
(H, but not H+, or not H2).
Next question coming …

19. sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5
Question 13
What is ionization?
A Molecules fall apart into atoms due to heat.
Glowing gas is formed.
B Nuclear processes in stars produce dangerous radiation.
C Atomic nuclei fall apart into neutrons and protons.
A neutron star results.
D Atoms lose (some of) their electrons due to heat or UV
radiation. The substance becomes plasma.
Next question coming …

20. sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5
Question 14
Why can “radiation” from power lines not
affect living organisms?
A Because power lines are usually well shielded.
B Because power lines radiate only electrons, which are
absorbed by a few inches of air.
C Because few photons are radiated from a power line.
D Because the energy of its each individual photon is tiny.
Next question coming …

21. sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5
Question 15
Which of the following causes a measurable amount of radiation, present on Earth?
The Solar Wind.
“Deep Space” cosmic rays.
Radiation from nuclear reactors.
Radiation from naturally occurring decays.
A I and III.
B II and IV.
C I, II and III.
D None of the above.
E All of the above.

22. Turn in your scantron now
personally!