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Stars/Radiative dynamo/Quiz

< Stars | Radiative dynamo

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.

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

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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   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

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Main resource: Hypotheses
  1. The dynamo lectures may be better as a part of a magnetohydrodynamics course.

See also

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{{Principles of radiation astronomy}}

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