# to these questions.

Electronics - Devices

Oct 18, 2013 (4 years and 6 months ago)

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Explain, using Maxwell’s
theory of electric and
magnetic fields, the answers
to these questions.

(1) Why is dielectric material
placed in a capacitor?

(2) Why does light reflect from a
glass surface?

(3) Why is the sky blue at noon?

(4) Relate F

to
E

and
B
.

(5) Determine
E

inside a moving
capacitor.

(6) Which Maxwell equation
describes an electric generator?

(7) What is a photon?

(8) Why are clouds white on a
partly cloudy day?

(9) How does the
plasma
frequency

in a plasma affect
electromagnetic waves?

(10) Describe the magnetic field
due to a moving change.

(11) Explain the levitating frog
demonstration on youtube.

(12) Why are sunsets red?

(13) How does the ionosphere
affect AM radio?

(14) Why do fishermen wear
polarized sunglasses?

(15) How far will a muon,
produced in the upper
atmosphere, travel before it
decays. Assume

= 100.

Grading Key:

Correct answer = 1 point.

Correct explanation in
terms of fields = 1 point.

Equations or quantitative
reasoning = 1 point.

3 points per problem

Dielectrics

Theory

Matter is atomic.

The atoms are polarized by an
electric field.

What is bound charge?

Applications

Capacitance = Q/V

Magnetism in materials

Theory

Matter is atomic.

The atoms are magnetized by a
magnetic field.

What is bound current?

Applications

A solenoid with an iron core

Boundary conditions of the
fields

You have two uniform regions of
space divided by a boundary.
What can you say about the
normal and tangential
components of the fields on
opposite sides of the boundary?

Time
-
dependent fields #1

Theory

Lenz’s law; the right
-
hand
rule.

Applications

inductance

electric power technology
(transformers and generators)

Kerst’s Betatron

Time
-
dependent fields #2

Theory

What are the consequences of
the displacement current?

Electromagnetic Waves in free
space

Transverse waves

Polarization

Energy density

Energy flux

Optics
--

EM waves and
matter

Light and transparent
dielectrics, like glass or
water

Light and metals

Light and a diffuse
plasma

Light scattering from
atoms.

Relativity and Electromagnetism

Covariant equations versus time
and space components.

Lorentz transformations of fields.

Particle dynamics

Equations of field transformations