Joseph von Fraunhofer discovered that a. passing light through a prism would create a rainbow b. light could behave as a particle c. there were dark lines in the colour spectrum made by the Sun
Absorption lines happen when a. a cool gas absorbs photons b. a hot gas releases photons c. photons pass through empty space
Scientists can study absorption lines to find out a. the masses of stars b. the distances between stars c. the chemicals present in stars
Discussion/essay questions
Do you know any interesting facts about light? What optical illusions or “tricks of the light” have you seen?
Transcript
In 1814, a German physicist named Joseph von Fraunhofer passed light from the Sun through a prism to create a colour spectrum. He noticed that there were dark lines blocking out certain colours in the spectrum. Today, scientists call these lines absorption lines. Absorption lines happen when particles of light, called photons, move through a cool gas. The atoms and molecules in the gas absorb some of the photons and block certain colours of light. When an atom absorbs a photon, it shows up as a dark line in the colour spectrum. The photons that get absorbed are not random. Every element absorbs specific wavelengths of light, which means every element also has a unique pattern of absorption lines. Scientists can study these lines to find out which chemicals are present in stars and planets.
The purpose of Schrödinger’s thought experiment was a. to study radioactive substances b. to demonstrate the durability of cats c. to show the flaws in a scientific theory
In the experiment, the poison would be activated by a. the movements of the cat b. the locking of the box c. the decaying of the substance
According to the theory, the experiment would cause a. the cat to die several times until someone opened the box b. the cat to stay alive until someone opened the box c. the cat to be both alive and dead until someone opened the box
Discussion/essay questions
Why do you think it is so easy to be misinformed about science? Do you think there is a solution to this?
Do you think it is important for the general population to be educated about scientific topics? Why or why not?
Transcript
“Schrödinger’s cat” is a thought experiment created by Austrian physicist Erwin Schrödinger. The purpose of the experiment was to show the flaws in a scientific theory suggesting that particles can only definitively change if someone is observing them. In Schrödinger’s example, a cat is locked in a box with a radioactive substance and a container of poison. If the substance decays, it activates the poison and kills the cat. Schrödinger argued that if the decaying of the substance could not happen until someone observed it, then the cat would be both alive and dead until someone opened the box. Although Schrödinger’s goal was to show how strange this idea was, many people misinterpreted him. This misunderstanding has caused some people to believe that it is possible for a cat to be both alive and dead.
An early model of the periodic table sorted elements by a. atomic number b. atomic weight c. number of subatomic particles
The first subatomic particle to be discovered was a. the electron b. the proton c. the neutron
A proton has a. a positive charge b. a negative charge c. no charge
Discussion/essay questions
Even though scientists did not yet understand subatomic particles, the early model that put elements in order of atomic weight still naturally grouped similar atoms together. Why do you think this is? Do you know any other historical examples of humans finding patterns that they didn’t understand?
Transcript
The periodic table is a system that scientists use to organize and classify chemical elements. Originally, many scientists tried to sort the elements by properties. One of the early models of the periodic table arranged elements by atomic weight, which naturally grouped elements with similar properties together. However, certain elements were outliers, and did not fit in their groups. In 1898, a scientist named J.J. Thomson discovered the electron, a subatomic particle with a negative charge. Later, in 1911, a scientist named Ernest Rutherford learned that electrons orbit a nucleus, which makes up most of the atom’s mass. Inside the nucleus, there are protons, which have a positive charge. An atom has an equal number of electrons and protons. This number became known as an element’s atomic number. Today, elements on the periodic table are arranged by atomic number, which gives a more accurate understanding of element properties.
Nuclear fusion is a type of reaction that turns one chemical element into another. The Sun and other use nuclear fusion as a form of power. In high enough , the nucleus of an atom can be separated from its electrons. The heat causes the nucleus to move very quickly. When two nuclei come close enough to each other, they fuse, forming a larger nucleus. This method allows stars to convert hydrogen atoms into helium atoms, and even more atoms after that. Nuclear fusion is a difficult to replicate on Earth, because it requires a lot of heat and pressure. However, many research groups around the world hope to find a way to use it as an source.
Comprehension questions
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Discussion/essay questions
Scientists are interested in nuclear fusion because it would be a clean and powerful energy source. Unlike the type of nuclear power we use today, nuclear fusion would not create dangerous waste. Can you think of any potential disadvantages to this type of energy?
Transcript
Nuclear fusion is a type of reaction that turns one chemical element into another. The Sun and other stars use nuclear fusion as a form of power. In high enough temperatures, the nucleus of an atom can be separated from its electrons. The heat causes the nucleus to move very quickly. When two nuclei come close enough to each other, they fuse, forming a larger nucleus. This method allows stars to convert hydrogen atoms into helium atoms, and even more complex atoms after that. Nuclear fusion is a difficult process to replicate on Earth, because it requires a lot of heat and pressure. However, many research groups around the world hope to find a way to use it as an energy source.
Because a superfluid has zero viscosity, it can move through tiny cracks and holes that a regular liquid can’t. How might that be a problem for scientists experimenting with superfluid helium?
Transcript
A superfluid is a unique type of liquid that has zero viscosity. This means that it will never stop flowing. The only type of liquid that scientists can turn into a superfluid is liquid helium. Helium is the only substance that stays in liquid form even as its temperature approaches absolute zero. Most substances freeze at much higher temperatures. When liquid helium is at a very low temperature, all of its atoms have the same amount of energy. This causes the substance to behave like one single atom instead of many. The atoms in superfluid helium don’t collide with each other, or transfer energy to each other. Because of this, there is no friction between the helium atoms. If a scientist decided to stir a container of superfluid helium, the liquid would continue to spin around the container forever.
