# 5 Electric and Magnetic Phenomena

Ηλεκτρονική - Συσκευές

18 Οκτ 2013 (πριν από 5 χρόνια και 2 μήνες)

142 εμφανίσεις

4/18/2012

1

Electric and Magnetic
Phenomena

Electric and magnetic phenomena
are related and have many practical
applications.

5a
: Direct Current

Students know how to predict the voltage or
current in simple direct current (
DC) electric
circuits constructed from batteries, wires,
resistors, and capacitors
.

Battery: provides
electric potential

Symbol: _________or_________

Resistor: slows
current
, changes electrical energy
to
heat

and/or
light

Symbol: ______

Wires: carry current through a circuit

Symbol:
lines

5b: Ohm’s Law

Students know how to solve problems
involving Ohm's law.

V = I R

V:
voltage

I:
current

R:
resistance

5c: Power

Students know any resistive element in a DC
circuit dissipates energy, which
heats

the
resistor. Students can calculate the power (rate
of energy dissipation) in any resistive circuit
element by using the formula P =
VI

=
I
2
R
.

5d: Transistors

Students know the properties of transistors
and the role of transistors in electric circuits.

Transistors modify
current

Often as an
amplifier

Transistors are used in
any electronic device

5e: Charges

Students know charged particles are sources
of electric fields and are subject to the forces
of the electric fields from other charges.

Charges are
negative

(extra electrons) or
positive

(lack of electrons

Opposite charges
attract

Like charges
repel

4/18/2012

2

5f: Magnetism

Students know magnetic materials and electric
currents (moving electric charges) are sources of
magnetic fields
and are subject to forces arising
from the magnetic fields of other sources.

North

and
South

Poles

Opposites
attract
, likes
repel

Moving charges
induce

a magnetic field

Magnetic fields
induce a force
on moving charges

5g: Induced Magnetic Field

Students know how to determine the direction
of a magnetic field produced by a current
flowing in a straight wire or in a coil.

Right Hand Rule

Thumb:
straight current in a wire
or
magnetic field in
a coil

Curled fingers:
magnetic field around a wire
or
current in a coil

5h: Induced Current

Students know changing magnetic fields
produce electric fields, thereby inducing
currents

in nearby conductors.

Current can be created in a wire without
anything directly
connected

to it

5i: Plasma

Students know plasmas, the fourth state of
matter, contain ions or free electrons or both
and
conduct electricity
.

Plasma:
superheated gas

Lightning

is plasma of air