Stars/Radiative dynamo/Quiz

File:Jupiter Dynamo.jpg

This is an image of a dynamo model suggested for the planet Jupiter. Credit: Robert MacDowall, NASA.

Radiative dynamo is a lecture and an article about a specific aspect of astrophysics applied to plasma, gaseous, liquid, and rocky objects. It is from the Radiation astronomy department initially for the course on the principles of radiation astronomy.

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Quiz

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1 True or False, The differential profile of the Sun's surface extends into the solar interior as rotating cylinders of constant angular momentum.

	TRUE
	FALSE

2 Complete the text:

Magnetic fields can be created in stratified (non-convective) layers in a rotating star.

3 True or False, A magnetic instability in the toroidal field (wound up by differential rotation) replaces the role of convection in opening the field amplification loop.

	TRUE
	FALSE

4 Complete the text:

Match up the characteristics with the type of dynamo:

disc dynamo - A

geodynamo - B

radiative dynamo - C

α dynamo - D

Ω dynamo - E

radiative α-Ω dynamo - F

Taylor-Spruit dynamo - G

convection .

pinch-type instabilites .

molten outer core .

turbulence, a radiative layer, and differential rotation .

radiative layers .

differential rotation .

a rotating cylinder .

5 True or False, For stars more massive than around 15 M_⊙ the Kelvin–Helmholtz turbulence dominates over the magnetic turbulence and a stable field cannot be sustained by a dynamo.

	TRUE
	FALSE

6 What are the requirements for a dynamo to occur and subsequently operate?

	plate tectonics in its past
	an electrically conductive fluid medium
	a spheroidal object
	stripes of crustal magnetism
	local magnetohydrodynamic instabilities
	transform faults
	shear between different parts
	two natural satellites
	an energy source

7 True or False, Any conversion of mechanical energy into electrical energy and associated magnetic fields is a dynamo.

	TRUE
	FALSE

8 Which of the following are associated with the dynamo of the Sun?

	plate tectonics in its past
	dipole magnetic field
	it is spheroidal
	stripes of crustal magnetism
	a circular electric current flowing deep within the star
	it appears to be in hydrostatic equilibrium
	transform faults
	shear between different parts of the Sun
	two natural satellites
	it has a radiative zone

9 True or False, Electrons in the Earth's magnetosphere are energized by neutral particles from the Sun

	TRUE
	FALSE

10 Which of the following are associated with the geodynamo of Mars?

	plate tectonics in its past
	Mars is spheroidal
	stripes of crustal magnetism
	it appears to be in hydrostatic equilibrium
	transform faults
	two natural satelites
	the direction of the magnetic field changes dramatically from place to place

11 True or False, An antidynamo theorem is one of several results that restrict the type of magnetic fields that may be produced by dynamo action.

	TRUE
	FALSE

12 Which phenomena are associated with the heliosphere?

	a region of space where the interstellar medium is blown away by the solar wind
	a bubble in space
	virtually all the material emanates from the Sun itself
	Voyager 2
	Voyager 1
	the termination shock

13 True or False, A dynamo taking place in the radiative layers of a star is a radiative dynamo.

	TRUE
	FALSE

14 A disc dynamo has which of the following characteristics?

	an alternating current
	an electrically insulating disc
	a uniform static magnetic field
	potential difference between the center of the disc and the magnetic field
	the disc rotates in a plane parallel to the magnetic field

15 True or False, No axisymmetric magnetic field can be maintained through a self-sustaining dynamo action by an axially symmetric current.

	TRUE
	FALSE

16 Which of the following is associated the Earth's geodynamo?

	the Sun and the Moon
	the Earth's magnetic field
	convection currents
	heat flow from the inner core
	ice ages
	plate tectonics
	the Coriolis force

17 True or False, The mathematical symbol $\nabla$ indicates a differential equation in which only one variable such as 'x' is differentiated.

	TRUE
	FALSE

18 Which geological phenomena are associated with Earth?

	lava-spewing volcanoes
	sulfur volcanoes
	plate tectonics
	water oceans
	liquid methane oceans
	silicate minerals

19 Yes or No, Motion resulting from a magnetodynamic instability may act as a dynamo to sustain a magnetic field.

	Yes
	No

20 Which phenomena are associated with the dynamo of Uranus?

	axisymmetric magnetic field
	sulfur volcanoes
	non-dipolar
	water oceans
	bipolar magnetotail
	detached bow shock
	obtuse rotation

Hypotheses

Main resource: Hypotheses

1. The dynamo lectures may be better as a part of a magnetohydrodynamics course.

See also

• Astronomy/Quiz
• Green astronomy/Quiz
• Planetary science/Quiz
• Radiation astrochemistry/Quiz
• Radiation astrogeography/Quiz
• Radiation astrohistory/Quiz
• Radiation astronomy/Quiz
• Theoretical radiation astronomy/Quiz

External links

• International Astronomical Union
• NASA/IPAC Extragalactic Database - NED
• NASA's National Space Science Data Center
• The SAO/NASA Astrophysics Data System
• SDSS Quick Look tool: SkyServer
• SIMBAD Astronomical Database
• SIMBAD Web interface, Harvard alternate
• Spacecraft Query at NASA.
• Universal coordinate converter

{{Principles of radiation astronomy}}