1. Regular Guest
Join Date
May 2005
Posts
30
Post Likes
Hello to all. I'm not clear on this two questions, please advise

"0" ohm reading across a switch means switched is closed? True or false

Infinity read across a switch means the switch is closed?
True or False

2. Regular Guest
Join Date
Apr 2003
Posts
469
Post Likes
True
"0" is a short

false
Infinity is an open

3. The way to think about it is that the ohm is a measurement of how hard electricity will have to travel to get across the path

For example 0 ohms would be you getting across your living room
Infinity is the same as you getting across the Atlantic with no boat

So although a 0 even though it would actually have some resistance if measured with a good meter
Would be closed
Same as a draw bridge you cant get across it if it is open and electricity cant get across a switch if it is open

Hope it helps and hope I didnt insult you by over simplifying it

4. Grumpy Old Man
Join Date
Apr 2003
Posts
6,383
Post Likes
If you are ever in doubt, touch your leads together and see what the meter says.

5. Originally posted by jultzya
If you are ever in doubt, touch your leads together and see what the meter says.
It is good practice, and could save your life some day, to switch your multimeeter to ohms and touch the leads together to check continuity through them every time you use your meter.

6. ## Roman

Think of a switch like a draw bridge -

When the drawbridge ( switch ) is closed - cars ( electrons ) can pass - The electrons from yur meter, for instance, passes through easily with very litle resistance - remembering that yur ohmmeter is looking for resistance - so very little resistance is close to none ( or zero )

When the drawbridge is open - no cars can pass - neither can electrons though an open switch. Bcause no current can pass, using ohms law, there must be a very high resistance between the two points of the switch. The meter sees this 'open' as a very high resistance - too high for the meter to read & WaLa, the meter shows 'infinity' or 'overload'.

Hope this helps and is not too confusing,
Richard

7. Banned
Join Date
Aug 2005
Posts
608
Post Likes
But is this true with both AC and DC electrical circuits ?

8. Professional Member
Join Date
Aug 2001
Posts
1,936
Post Likes
is there a diff between ac and dc circuits

9. yes ed there is
one starts with an "A" and the other starts with a "D"

10. Banned
Join Date
Aug 2005
Posts
608
Post Likes
Yes, AC stands for "alternating current"

and DC stands for " direct current"

I'm glad to see that there is a lot of talk on electricity here, I did some time in class on electrical stuff. So I may be able to help you out a little if you need it.

11. Professional Member
Join Date
Aug 2001
Posts
1,936
Post Likes
i thought it was the circuits that was being discussed not the titles

12. Banned
Join Date
Aug 2005
Posts
608
Post Likes
Its like this Ed if we incorporate the whole ac dc theory into the draw bridge theory, it would come out something like this, when the draw bridge closes the cars
( electrons ) can pass to the other side. Which is fine, the difference is that if the cars are in a AC electrical circuit they will be changing lanes as they cross over the bridge ( weaving ) where as in a DC circuit they will cross the bridge in a single file line.

Hope this makes it easier.

13. Professional Member
Join Date
Aug 2001
Posts
1,936
Post Likes
changing lanes or direction of travel

Page 1 of 2 12 Last

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•

## Related Forums

The place where Electrical professionals meet.