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#4719765 - 04/07/18 05:50 PM Electrical Circuit Questions
das_peikko Offline


Registered: 01/01/18
Posts: 534
Loc: San Antonio, TX
Would anybody care to answer the questions?

Circuit 1


Circuit 2

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#4719793 - 04/07/18 06:15 PM Re: Electrical Circuit Questions [Re: das_peikko]
mk378 Offline


Registered: 09/27/15
Posts: 1450
Loc: 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.


Edited by mk378 (04/07/18 06:18 PM)

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#4719819 - 04/07/18 06:46 PM Re: Electrical Circuit Questions [Re: das_peikko]
das_peikko Offline


Registered: 01/01/18
Posts: 534
Loc: San Antonio, TX
Thank You mk378. I appreciate it very much. smile

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#4719862 - 04/07/18 07:32 PM Re: Electrical Circuit Questions [Re: das_peikko]
Ducked Offline


Registered: 10/25/12
Posts: 4432
Loc: Taiwan
When ah were a lad, we 'ad to doo ower OWN 'omework.

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

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#4719947 - 04/07/18 08:37 PM Re: Electrical Circuit Questions [Re: mk378]
SR5 Online   content


Registered: 07/07/15
Posts: 4530
Loc: 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.
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#4719966 - 04/07/18 08:59 PM Re: Electrical Circuit Questions [Re: mk378]
JHZR2 Offline



Registered: 12/14/02
Posts: 41906
Loc: 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

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#4720083 - 04/07/18 11:36 PM Re: Electrical Circuit Questions [Re: mk378]
KJSmith Offline


Registered: 08/31/15
Posts: 271
Loc: 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.



Edited by KJSmith (04/07/18 11:38 PM)

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#4720285 - 04/08/18 08:19 AM Re: Electrical Circuit Questions [Re: KJSmith]
SHOZ Offline


Registered: 06/28/03
Posts: 5824
Loc: 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.
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#4720306 - 04/08/18 08:45 AM Re: Electrical Circuit Questions [Re: SHOZ]
eljefino Offline


Registered: 06/15/03
Posts: 32776
Loc: 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.

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#4720307 - 04/08/18 08:46 AM Re: Electrical Circuit Questions [Re: eljefino]
SHOZ Offline


Registered: 06/28/03
Posts: 5824
Loc: 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.
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#4720535 - 04/08/18 12:52 PM Re: Electrical Circuit Questions [Re: das_peikko]
berniedd Offline


Registered: 03/24/08
Posts: 596
Loc: 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.

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#4721240 - 04/09/18 07:41 AM Re: Electrical Circuit Questions [Re: mk378]
Number_35 Offline


Registered: 07/07/14
Posts: 841
Loc: 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

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#4724092 - 04/11/18 08:58 PM Re: Electrical Circuit Questions [Re: SHOZ]
sleddriver Offline


Registered: 02/06/10
Posts: 4722
Loc: 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.
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#4724394 - 04/12/18 07:32 AM Re: Electrical Circuit Questions [Re: das_peikko]
Virtus_Probi Offline


Registered: 06/25/15
Posts: 4068
Loc: New England
I tried running SPICE on this and it wouldn't converge.
;^)
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