L
[email protected]
- Jan 1, 1970
- 0
Hi,
I'm pretty new to this stuff. I'm trying to teach myself with "Lessons
In Electric Circuits" over at ibiblio.org.
Anyway, I've made it to Chapter 6 in Book 1, and I'm a little confused
about a voltage polarity example. An image of the circuit I'm confused
about can be found at:
http://www.ibiblio.org/obp/electricCircuits/DC/00117.png
The author says that the voltage between points 3 and 4 is +/- 32,
depending on whether you're measuring point 3 with respect to point 4,
or vice versa. This doesn't seem very intuitive to me...
It seems like the voltage between the two points should be
(35V-20V)-(25V-13V) = 15V-12V = 3V. I got that number by calculating
the voltage of point 3 with respect to point 8 (20V drop across
resistor), and the voltage of point 4 with respect to point 5 (13V drop
across resistor), then subtracting them because "voltage is relative."
Then again, I don't understand why you have to connect points 8 and 9
(while not connecting points 3 and 4) in order to use Kirchhoff's Law,
or how this circuit would actually work in real life, so that's
probably why I just don't get it. Can somebody help me out?
Thank you very much.
I'm pretty new to this stuff. I'm trying to teach myself with "Lessons
In Electric Circuits" over at ibiblio.org.
Anyway, I've made it to Chapter 6 in Book 1, and I'm a little confused
about a voltage polarity example. An image of the circuit I'm confused
about can be found at:
http://www.ibiblio.org/obp/electricCircuits/DC/00117.png
The author says that the voltage between points 3 and 4 is +/- 32,
depending on whether you're measuring point 3 with respect to point 4,
or vice versa. This doesn't seem very intuitive to me...
It seems like the voltage between the two points should be
(35V-20V)-(25V-13V) = 15V-12V = 3V. I got that number by calculating
the voltage of point 3 with respect to point 8 (20V drop across
resistor), and the voltage of point 4 with respect to point 5 (13V drop
across resistor), then subtracting them because "voltage is relative."
Then again, I don't understand why you have to connect points 8 and 9
(while not connecting points 3 and 4) in order to use Kirchhoff's Law,
or how this circuit would actually work in real life, so that's
probably why I just don't get it. Can somebody help me out?
Thank you very much.