Astm Lab PDF answers
The Sun
Warning: Never look at the Sun without the proper equipment.
Introduction Below is diagram showing the layers of the Sun that can be directly observed. We can only “see” into the interior with sophisticated techniques such as helioseismology.
Region of the Sun Thickness (km) Density (kg/m3) Temperature (K)
Core to Photosphere 696,000 150,000 at core 15 million at core
Photosphere 500 2 x 10-4 5800
Chromosphere 1500 5 x 10-6 4500
Corona about 1 million (turns into the
Solar Wind)
10-12 1 million
Jet passing in front of the Sun
Sunspot
1) The Spectrum of Hydrogen The Bohr-model of the hydrogen atom says that the electron can only exist in specific Energy States. Each Energy State is identified by a number (n = 1, 2, 3…), where the lowest energy state is n=1, and all other states (n=2,3,4,5…) are called an Excited State. The energy of an electron increases with higher states (n).
Visible Light production by Hydrogen Gas. In the back of the room there is a tube of hydrogen gas that is emitting a pink-violet color. The hydrogen gas inside the tube is excited by a high voltage which forces some electrons out of their lowest energy state. After a short time, the electrons fall from their excited state to lower energy states. A photon is released that has the energy exactly equal to the difference in energy between the electron’s final state and its initial state.
The visible light coming out of the hydrogen tube is light made up of four distinct colors. One type of photon has less energy (Red), another has medium energy (Blue-Green), and the third and fourth types have the highest energy (Violet). Use the raw spectrum data PDF for seeing the hydrogen spectrum.
2) Other Elements Observe the other elements provided in the raw spectrum data PDF and record the colors and wavelengths of these colors on the answer sheet.
3) The Hydrogen Atom and a Loop of Wire Just as the hydrogen atom can emit only photons with specific frequencies, the hydrogen atom can absorb only photons with those same specific frequencies. Louis de Broglie theorized that an electron is a wave and the electron in a hydrogen atom is a standing wave. An electron in a hydrogen atom can change its energy state when it absorbs the exact energy necessary to add another wave. A similar situation happens when vibrating a loop of wire. If the wire vibrates at a resonant frequency the wire will absorb energy and produce a standing wave with
nodes, but if you shake it at any non-resonant frequency nothing happens.
Adjust the Function Generator by following the instructions
• Turn the Amplitude knob to Min. (Minimum)
• Turn on the Switch On (located on the back of the Function Generator)
• Turn the Adjust knob clockwise until the frequency displayed is 1 Hz
• Slowly turn the Amplitude knob counter–clockwise until you can see the loop move up and down once each second, because 1 Hz = 1 Hertz = 1(vibration/second)
• IMPORTANT – If the loop starts shaking too much it will break. Turn the Amplitude knob toward Min. if the vibration becomes too large.
• Slowly turn the Adjust knob until you see 3 and 5 nodes. Record the frequency.
4) Estimate the size of a large sunspot group Below is an image of sun showing the largest sunspot group ever, photographed from Mt. Wilson - April 7, 1947.
The diameter of the Sun is 1.4x106 km and the diameter of the Earth is 12800 km. What is the Diameter of the Sun in Earth Diameters?
Use a ruler estimate the largest size of the large sunspot group.
(Sun Diameter)=
____x (Earth Diameters)
(Large Sunspot size) = ____ x (Earth Diameters)
5) The Sun’s rotation
Find the rotation rate of the sun by estimating the longitude of sunspots and fill in Table 5.1 on the answer sheet. Hint: (Sunspot Rotation Rate) = (change in longitude from Jun 23 to 29) / (6 days)
5.2 The images of the Sun were taken from Earth. Between June 23 and June 29 the Earth moved in its orbit as it revolved around the sun. Find the Sidereal-Rotation- Rate of the Sun by accounting for the Earth’s motion in your answers. (note: The direction of the Earth’s revolution is the same as the direction of the Sun rotation. )
5.3 Calculate the Rotation Period of the Sun by dividing (360°) by the Sidereal Rotation Rate you recorded for sunspot-B in Table 5.2. 5.4 Unlike terrestrial planets, the Sun does not rotate with the same rate for every latitude. Examine table 5.2 and circle one:
Movies: You will find the movies on your computer.
6) Eclipse.mpg A solar eclipse at a FASTER than normal rate. May 10, 1994 Bloomington, Indiana 6.1 What type of eclipse is it?
i) Total Eclipse ii) Annular Eclipse iii) Partial Eclipse
6.2 The Sun has an angular size of 0.5°, and the moon revolves around the Earth at
approximately 0.5°/hour. Use this information to estimate the elapsed time of the eclipse, from when the Moon begins to cover the Sun until the Moon does not cover the Sun. You can ignore the Earth’s rotation.
7) Granulation.mpg
This movie shows a magnified view of the photosphere. Granulation occurs because hot gas rises in the middle and cool gas sinks along the edge. This method of transporting energy is called convection. Another way to say it is the
surface is boiling, rising up at about 1 km/s. 35 minutes elapsed during the filming, but you are watching it compressed to a few seconds. One edge of the movie is equal to 25,000 km. [Note: Sunspots appear darker because magnetic fields keep the hot gas from boiling up, the surface cools and becomes a dark area.]
8) Coronal Mass Ejection.mpg
Watch the movie and note:
• The material that is ejected from the Sun’s corona is called a Coronal Mass Ejection (CME).
• A comet is destroyed when it move close to the Sun.
• The background stars that make up the Milky Way.
Disk in telescope
to block the Sun’s
photosphere
Sun’s corona
Background Stars
(The Milky Way)
9) CME animation.mpg Animation of a coronal mass ejection (CME) and the interaction with Earth