# electric field in a circuit

Discussion in 'Electronic Design' started by ERICA, Apr 11, 2004.

1. ### ERICAGuest

why electric field is zero in non-resistive part but non-zero in resistive part?
and why whenever a p.d is applied, there is an electric field?

2. ### Rheilly PhoullGuest

It is because students in HK do not do their homework due to playing on the

3. ### Fred BloggsGuest

Electric field results from sources of charge density resulting from an
input energy required to establish the source separation in space- hence
the "p.d.". There can be no field gradient in a "non-resistive part"- by
which I understand you to mean perfect conductor- because ****by
definition of a perfect conductor*** there can be no such charge
inappropriate to this forum. Take it to sci.physics.

4. ### Roger_NickelGuest

Because we define it to be so. If you want to use some other model, go

5. ### ERICAGuest

I am sorry to bring so much inconvenience to you .Thanks a lot for
posting tnem next time.

6. ### Edward E. HopkinsGuest

Don't worry about the newsgroup grumps ... these are good questions but
maybe there is a more educational oriented newsgroup ... think about the
current flowing through a perfect wire (i.e. zero resistance) ... there is
no voltage drop. Technically there would be a field according to right hand
rule encircling the wire ... with a resistive component you will be
resisting the flow which removes energy from the system in the form of heat.
You need to get a good book on electronics and look at the math equations
for RC and LRC circuits. Have you ever built an electromagnet? That will
be the best intuitive explanation of this physics effect ... take a heavy
iron nail and wrap it tightly with copper wire. Attach both ends of the
wire to a battery and you can lift at least paper clips.

Ed

7. ### ERICAGuest

thank you very much for your useful comment. i have tried to build an
electromagnet and now i know the answer. in fact, i have never
throught of using magnetism to explain the question in circuit...
again, thanks a lot, next time i will try to relate different topics
up to explain questions. i think i will enjoy reading electronics
books.