Space Plasma Physics Final Exam Review
2026 Questions and Answers Graded A+
Plasma - Correct answer-quasi-neutral gas of charged particles showing collective
behavior when stationary
quasi-neutral - Correct answer-balanced electron and ion number densities; n_e ~=
Zn_i
collective behavior - Correct answer-long range of Coulomb potential
(q/4*pi*eps_0*r) gives nonlocal influence of equilibrium disturbances;
macroscopic fields dominate microscopic fluctuations
Debye length - Correct answer-λ_D; how far the electrostatic effect persists; Scale
over which electric fields are screened in a plasma
first plasma criterion - Correct answer-plasma quasi-neutrality depends on physical
system dimension L >> Debye length λ_D
second plasma criterion - Correct answer-plasma parameter Λ = n_e*λ_D^3 >> 1
third plasma criterion - Correct answer-electrons remain unaffected by collisions;
ω_pe*τ_n >> 1
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, plasma frequency - Correct answer-Natural oscillation frequency of electrons in a
plasma
Magnetohydrodynamics - Correct answer-Fluid description of plasma treating it as
a conducting fluid
Frozen in-flux theorem - Correct answer-Magnetic field lines move with the
plasma (valid for high magnetic Reynolds number)
Magnetic Reynolds Number - Correct answer-Ratio of advection to diffusion of
magnetic field; determines frozen-in validity; tells if medium is dominated by
diffusion or flow
E × B Drift - Correct answer-Plasma drift perpendicular to both electric and
magnetic fields
Gyroradius - Correct answer-Radius of charged particle circular motion in
magnetic field
Cyclotron Frequency - Correct answer-Frequency of particle gyration around
magnetic field lines
magnetosphere - Correct answer-between magnetosheath and terrestrial magnetic
field; Region where planetary magnetic field dominates over solar wind
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2026 Questions and Answers Graded A+
Plasma - Correct answer-quasi-neutral gas of charged particles showing collective
behavior when stationary
quasi-neutral - Correct answer-balanced electron and ion number densities; n_e ~=
Zn_i
collective behavior - Correct answer-long range of Coulomb potential
(q/4*pi*eps_0*r) gives nonlocal influence of equilibrium disturbances;
macroscopic fields dominate microscopic fluctuations
Debye length - Correct answer-λ_D; how far the electrostatic effect persists; Scale
over which electric fields are screened in a plasma
first plasma criterion - Correct answer-plasma quasi-neutrality depends on physical
system dimension L >> Debye length λ_D
second plasma criterion - Correct answer-plasma parameter Λ = n_e*λ_D^3 >> 1
third plasma criterion - Correct answer-electrons remain unaffected by collisions;
ω_pe*τ_n >> 1
©COPYRIGHT 2025,ALL RIGHTS RESERVED 1
, plasma frequency - Correct answer-Natural oscillation frequency of electrons in a
plasma
Magnetohydrodynamics - Correct answer-Fluid description of plasma treating it as
a conducting fluid
Frozen in-flux theorem - Correct answer-Magnetic field lines move with the
plasma (valid for high magnetic Reynolds number)
Magnetic Reynolds Number - Correct answer-Ratio of advection to diffusion of
magnetic field; determines frozen-in validity; tells if medium is dominated by
diffusion or flow
E × B Drift - Correct answer-Plasma drift perpendicular to both electric and
magnetic fields
Gyroradius - Correct answer-Radius of charged particle circular motion in
magnetic field
Cyclotron Frequency - Correct answer-Frequency of particle gyration around
magnetic field lines
magnetosphere - Correct answer-between magnetosheath and terrestrial magnetic
field; Region where planetary magnetic field dominates over solar wind
©COPYRIGHT 2025,ALL RIGHTS RESERVED 2
