Download Chapter 23 Circuits

Chapter 23
Circuits
Topics:
• 
• 
• 
Circuits containing multiple
elements
Series and parallel
combinations
Electricity in the nervous
system
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Drawing Circuit Diagrams
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Checking Understanding
The following circuit has a battery, two capacitors and a resistor.
Which of the following circuit diagrams is the best representation of
the above circuit?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Answer
The following circuit has a battery, two capacitors and a resistor.
Which of the following circuit diagrams is the best representation of
the above circuit?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Kirchhoff’s Laws
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Using Kirchhoff’s
Laws
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
The diagram below shows a segment of a circuit. What is the
current in the 200 resistor?
A.  0.5 A
B.  1.0 A
C.  1.5 A
D.  2.0 A
E.  There is not enough information to decide.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Answer
The diagram below shows a segment of a circuit. What is the
current in the 200 resistor?
B. 1.0 A
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Series Resistors
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Parallel Resistors
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Electricity in the Nervous System
Understanding electrical signals in
the nervous system.
The long fibers in the connecting
the nerve cells in the picture are
called axons, and they transmit
electric signals between cells.
We start by discussing the latter
(nerve cells)
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Model of a nerve cell
Cell membrane: separates regions of
conducting fluid inside and outside the
cell.
Mainly two (positive) ions, potassium
(K) and sodium (Na) move in and out.
Two mechanisms for this:
- K-NA exchange
- K-NA channels
This charge separation produces a
potential difference between inside
and outside of the cell and an
electric field in the membrane.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
The cell’s resting potential
The electric potential is
produced
by a charge separation.
The membrane becomes
polarized.
When there is no activity (rest)
the potential difference is
typically around 70mV (being
smaller inside)
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Electricity in the Nervous System
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
The propagation of nerve impulses
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Saltatory Conduction
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.