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Electrical Circuit Questions #4719765
04/07/18 04:50 PM
04/07/18 04:50 PM
Joined: Jan 2018
Posts: 540
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP
Joined: Jan 2018
Posts: 540
San Antonio, TX
Would anybody care to answer the questions?

Circuit 1


Circuit 2

Re: Electrical Circuit Questions [Re: das_peikko] #4719793
04/07/18 05:15 PM
04/07/18 05:15 PM
Joined: Sep 2015
Posts: 1,631
USA
mk378 Offline
mk378  Offline
Joined: Sep 2015
Posts: 1,631
USA
An ideal closed switch or un-blown fuse has zero resistance, thus zero volts for V2 and V3 in the first circuit.

Circuit is working correctly so we can assume these:

V1 Battery: charged = 12 volts. Of course a real battery is not exactly 12 volts.
V2 Fuse: not blown = zero volts.
V3 Switch: closed = zero volts
V4 Bulb: not burnt out = gets battery voltage minus the drop across the resistor, so 6 volts.

In circuit 2, the switch is open, so the entire battery voltage will appear across the switch (V3). Everything downstream of the switch is turned off, zero volts.

Last edited by mk378; 04/07/18 05:18 PM.
Re: Electrical Circuit Questions [Re: das_peikko] #4719819
04/07/18 05:46 PM
04/07/18 05:46 PM
Joined: Jan 2018
Posts: 540
San Antonio, TX
das_peikko Offline OP
das_peikko  Offline OP
Joined: Jan 2018
Posts: 540
San Antonio, TX
Thank You mk378. I appreciate it very much. smile

Re: Electrical Circuit Questions [Re: das_peikko] #4719862
04/07/18 06:32 PM
04/07/18 06:32 PM
Joined: Oct 2012
Posts: 4,825
Taiwan
Ducked Offline
Ducked  Offline
Joined: Oct 2012
Posts: 4,825
Taiwan
When ah were a lad, we 'ad to doo ower OWN 'omework.

Tell that te kids today, they'll not believe yoo.

Re: Electrical Circuit Questions [Re: mk378] #4719947
04/07/18 07:37 PM
04/07/18 07:37 PM
Joined: Jul 2015
Posts: 4,658
Down Under
SR5 Offline
SR5  Offline
Joined: Jul 2015
Posts: 4,658
Down Under
Originally Posted By: mk378
An ideal closed switch or un-blown fuse has zero resistance, thus zero volts for V2 and V3 in the first circuit.

Circuit is working correctly so we can assume these:

V1 Battery: charged = 12 volts. Of course a real battery is not exactly 12 volts.
V2 Fuse: not blown = zero volts.
V3 Switch: closed = zero volts
V4 Bulb: not burnt out = gets battery voltage minus the drop across the resistor, so 6 volts.

In circuit 2, the switch is open, so the entire battery voltage will appear across the switch (V3). Everything downstream of the switch is turned off, zero volts.

Yes that looks like a good answer to me and well explained. Nice work.

I'll just add that the assumption is an ideal volt meter that offers infinite resistance, so it doesn't steal any voltage when taking a measurement.


---------------------------------------------------------------------------------
Castrol GTX Ultraclean 15W40 A3/B3 + Wesfil-Cooper Z154
Re: Electrical Circuit Questions [Re: mk378] #4719966
04/07/18 07:59 PM
04/07/18 07:59 PM
Joined: Dec 2002
Posts: 42,459
New Jersey
JHZR2 Offline
JHZR2  Offline
Joined: Dec 2002
Posts: 42,459
New Jersey
Originally Posted By: mk378
An ideal closed switch or un-blown fuse has zero resistance, thus zero volts for V2 and V3 in the first circuit.

Circuit is working correctly so we can assume these:

V1 Battery: charged = 12 volts. Of course a real battery is not exactly 12 volts.
V2 Fuse: not blown = zero volts.
V3 Switch: closed = zero volts
V4 Bulb: not burnt out = gets battery voltage minus the drop across the resistor, so 6 volts.

In circuit 2, the switch is open, so the entire battery voltage will appear across the switch (V3). Everything downstream of the switch is turned off, zero volts.


+1

Re: Electrical Circuit Questions [Re: mk378] #4720083
04/07/18 10:36 PM
04/07/18 10:36 PM
Joined: Aug 2015
Posts: 325
TX
KJSmith Offline
KJSmith  Offline
Joined: Aug 2015
Posts: 325
TX
Originally Posted By: mk378
V4 Bulb: not burnt out = gets battery voltage minus the drop across the resistor, so 6 volts.

Circuit 1
Looks like V4 is reading to ground.
Bulb condition does not matter.


Last edited by KJSmith; 04/07/18 10:38 PM.
Re: Electrical Circuit Questions [Re: KJSmith] #4720285
04/08/18 07:19 AM
04/08/18 07:19 AM
Joined: Jun 2003
Posts: 5,973
Illinois
SHOZ Offline
SHOZ  Offline
Joined: Jun 2003
Posts: 5,973
Illinois
Originally Posted By: KJSmith
Originally Posted By: mk378
V4 Bulb: not burnt out = gets battery voltage minus the drop across the resistor, so 6 volts.

Circuit 1
Looks like V4 is reading to ground.
Bulb condition does not matter.

And picture two would be a dead short to ground when the switch is closed.


2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual
Re: Electrical Circuit Questions [Re: SHOZ] #4720306
04/08/18 07:45 AM
04/08/18 07:45 AM
Joined: Jun 2003
Posts: 33,776
ME
eljefino Offline
eljefino  Offline
Joined: Jun 2003
Posts: 33,776
ME
Originally Posted By: SHOZ

And picture two would be a dead short to ground when the switch is closed.


nope 'cuz V4 is a sample point not a load.

Re: Electrical Circuit Questions [Re: eljefino] #4720307
04/08/18 07:46 AM
04/08/18 07:46 AM
Joined: Jun 2003
Posts: 5,973
Illinois
SHOZ Offline
SHOZ  Offline
Joined: Jun 2003
Posts: 5,973
Illinois
Originally Posted By: eljefino
Originally Posted By: SHOZ

And picture two would be a dead short to ground when the switch is closed.


nope 'cuz V4 is a sample point not a load.
Then they used the wrong symbol and should show the volt meter in there. Unless it was so described in the original paper.


2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual
Re: Electrical Circuit Questions [Re: das_peikko] #4720535
04/08/18 11:52 AM
04/08/18 11:52 AM
Joined: Mar 2008
Posts: 624
A Warm place to live in
berniedd Offline
berniedd  Offline
Joined: Mar 2008
Posts: 624
A Warm place to live in
Eljefino is correct. V4 is a voltmeter and is not a short to ground. Much the same as V1 across the battery that reads its voltage.

Re: Electrical Circuit Questions [Re: mk378] #4721240
04/09/18 06:41 AM
04/09/18 06:41 AM
Joined: Jul 2014
Posts: 1,075
Winnipeg MB CA
Number_35 Online content
Number_35  Online Content
Joined: Jul 2014
Posts: 1,075
Winnipeg MB CA
Originally Posted By: mk378
An ideal closed switch or un-blown fuse has zero resistance, thus zero volts for V2 and V3 in the first circuit.

Circuit is working correctly so we can assume these:

V1 Battery: charged = 12 volts. Of course a real battery is not exactly 12 volts.
V2 Fuse: not blown = zero volts.
V3 Switch: closed = zero volts
V4 Bulb: not burnt out = gets battery voltage minus the drop across the resistor, so 6 volts.

In circuit 2, the switch is open, so the entire battery voltage will appear across the switch (V3). Everything downstream of the switch is turned off, zero volts.

Agreed. (Ducked, are you one of the four Yorkshiremen?) smile

Re: Electrical Circuit Questions [Re: SHOZ] #4724092
04/11/18 07:58 PM
04/11/18 07:58 PM
Joined: Feb 2010
Posts: 4,838
Central Texas
sleddriver Offline
sleddriver  Offline
Joined: Feb 2010
Posts: 4,838
Central Texas
Originally Posted By: SHOZ
And picture two would be a dead short to ground when the switch is closed.
No.
Ideal Volt meter has infinite internal resistance/V. Otherwise it'll load down the CUT and give a false reading.


1998 Volvo V70 T5 228,880 mi. Original Owner.
M1 10W-30 HM
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Re: Electrical Circuit Questions [Re: das_peikko] #4724394
04/12/18 06:32 AM
04/12/18 06:32 AM
Joined: Jun 2015
Posts: 4,562
New England
Virtus_Probi Offline
Virtus_Probi  Offline
Joined: Jun 2015
Posts: 4,562
New England
I tried running SPICE on this and it wouldn't converge.
;^)


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