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!

Review questions coming …

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 …

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 …

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.

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

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

Questions coming …

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 …

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 …

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 …

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 …

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.

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 - 2,000 K falls apart into atoms (gas ) T > 2,000 - 3,000 K atoms are ionized (plasma) (Note: H and He need much higher temperature to ionize, T > 10,000 K)

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

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)

Questions coming …

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 …

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 …

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 …

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.

Turn in your scantron now personally!