Electrical Circuit Questions

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Would anybody care to answer the questions?

Circuit 1
27432373228_ee076e9fb4_z.jpg


Circuit 2
27432373148_69037a2e11_z.jpg
 
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:
When ah were a lad, we 'ad to doo ower OWN 'omework.

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