Questions on Sun - Earth Interactions

Here are some questions to get you started. Additional questions will be added over coming months so please check back soon. Click on the blue answer tags for answers or guidance on questions.

  1. A free neutron undergoes beta decay, producing a high-energy beta particle (electron), a proton and an electron antineutrino.
    a) How does the original mass of the neutron compare with the combined mass of all the products?
    b) Account for any difference.
    c) What is the mass number and atomic number for a neutron?
    d) What is the total mass number and atomic number for the products?
    e)What does this suggest about mass numbers and atomic numbers in nuclear reactions?

    a) The mass of the neutron is slightly heavier than the combined mass of the proton, electron and electron antineutrino,
    b) This difference arises due to fact that a small amount of mass is converted into energy in the decay process (Einstein's E = m.c2). Most of this is carried off as the high kinetic energy of the beta particle.
    c) A neutron has a mass number of 1 and an atomic number of 0.
    d) An electron antineutrino has zero mass number and zero atomic number, the beta particle, being an electron, has a mass number of 0 and an atomic number of -1, the proton has a mass number of 1 and an atomic number of +1. This means that the combined atomic number is -1 + 1 = 0, ie the same as the neutron. The combined mass number is 0 +1 = +1, ie the same as that of the neutron.
    e) Both mass number and atomic number are conserved quantities in nuclear reactions.
  2. Uranium-238 is a naturally occuring radioisotope. It undergoes α decay, producing Thorium-234 as a daughter nucleus which in turn undergoes β decay, producing Protactinium-234. This so-called decay sequence continues through a number of radioisotopes until a stable isotope of another element is eventually reached. Starting from Pa-234 the decay sequence involves the following decay: β,α, α, α, α, α, β,β,α, β,β, α.
    a)Identify each of the daughter nuclei produced in the decay sequence including the final, stable end isotope.
    b)What else is likely to be emitted in several of the decay steps?

    a) U-234, Th-230, Ra-226, Rn-222, Po-218, Pb-214, Bi-214, Po-214, Pb-210, Bi-210, Po-210, Pb-206.
    b) Often a beta or alpha decay is accompanied by gamma emission form the daughter nuclei.
  3. The tracks of two emissions from two radioisotopes are recorded as they pass through a magnetic field as shown in the following diagram. Identify which type of radiation is responsible for each of the tracks, A and B.

    Question 3 image.

    The track 'A' is undeflected and corresponds to the path that would be followed by a gamma ray. Track B is deflected in the same direction as that which would be experienced by a positively charged particle so it is likely to be caused by an alpha particle.
  4. Smoke detectors are now fitted inside most homes and other buildings. They have a radioisotope in them that emits alpha particles. Why are they safe to use in homes?

    Alpha particles can only travel a few centimetres (about 5) in air on average before losing all their energy and gaining electrons to form an inert, low-energy helium atom. Given that they are normally mounted on ceilings and are encased by plastic and metal, there is no risk that the alpha radiation will penetrate the detector and pose a risk to anyone. The actual amount of the radio isotope source, usually Americium-241, is also very small.
  5. Account for the high penetration property of gamma rays.

    Gamma rays are high-energy (ie very high frequency and consequently very short wavelength) photons of electromagnetic radiation. As they have no charge they do not interact with either magnetic or electric fields so have to actually collide with a particle to interact with it. Given they have zero rest mass their chances of collision are much lower than the more massive beta and alpha particles so they are more likely to travel further before a collision occurs.
  6. Leaks in underground pipes can sometimes be detected by injecting a radioisotope in a fluid along the pipe. Explain what type of emitter would be best for this purpose.

    The radioisotope would have to be a gamma-emitter as only gamma rays have sufficient penetration to be able to pass through the wall of the pipe and the earth above to an above ground detector.
  7. This diagram shows the averaged sunspot number from 1610 to 2000.

    Yearly Averaged Sunspot Numbers, 1610 - 2000

    a) What are no sunspot numbers recorded before 1610?
    b) What is significant about the period 1650 - 1700 and what is it called?
    c) What was the associated impact on Earth of this?

    a) Sunspots were only systematically observed and recorded following Galileo's publication of his telescopic observations in 1610.
    b) The period, known as the Maunder Minimum, corresponds to a period of extremely low sunspot activity, with mostly no or only a few sunspot groups observed.
    c) This decline in solar activity resulted in about a 1% drop in solar radiation incident on the Earth. One consequence of this was a slight drop in average temperature, noticeable through the recorded harsh winters in northern Europe in this period (the 'Little Ice Age').
  8. What protects the Earth from the worst effects of the solar wind?

    The Earth's magnetosphere deflects most of the charged particles from the Sun. The ozone in our upper atmosphere absorbs the UV radiation. X-rays are also absorbed by our atmosphere.
  9. What is one visible indicator on Earth of increased solar activity or intense solar storms?

    Aurorae in the upper atmosphere, visible from higher latitudes, are due to collisions between high energy charged particles from the solar wind with molecules and atoms in the atmosphere. The resultant light show is visible from the ground at night.
  10. Why do satellites require specially-hardened or protected electrical components and circuitry?

    Charged particles and high energy photons from the solar wind and cosmic rays from elsewhere in the Universe can damage electrical circuits.
  11. Which region of Australia is potentially most at risk from increased solar storm activity?

    Tasmania is further south than the rest of the nation and is thus closer to the magnetic polar region. Due to the channeling of charged particles into this region there is greater chance of problems such as overloading of electrical power distribution systems during a severe solar storm.