The voltage between two points

[dev_maghraby]

TL;DR Summary

An electrical circuit with three resistors and a battery connected in series. After the first two resistors, there is a point connected to the ground. Why is the voltage difference between the ground point and the positive of the battery not 10 volts?

In electrical circuit there are three resistors and a battery connected in series. After the first two resistors, there is a point connected to the ground. Why is the voltage difference between the ground point and the positive of the battery not 10 volts?

In that circuit, I think that the voltage of point B is 0 volts because it is touching the ground, and also the voltage of point S is 10 volts because it is connected directly to the battery, but why is the voltmeter reading not equal to 10 volts What is the difference between the voltage of points S and B?

 

[DaveE]

TL;DR Summary: An electrical circuit with three resistors and a battery connected in series. After the first two resistors, there is a point connected to the ground. Why is the voltage difference between the ground point and the positive of the battery not 10 volts?

In electrical circuit there are three resistors and a battery connected in series. After the first two resistors, there is a point connected to the ground. Why is the voltage difference between the ground point and the positive of the battery not 10 volts?

IDK, why isn't it 137V? 4V? -17V? How would we know?
Schematic please, with component values. You can just draw it on paper, take a (readable) photo and post it.
Seriously, reread your question and consider if it's understandable. We are not clairvoyant.

'They' say there's no bad questions... 'They' didn't see this one, I guess.

 

[dev_maghraby]

IDK, why isn't it 137V? 4V? -17V? How would we know?
Schematic please, with component values. You can just draw it on paper, take a (readable) photo and post it.
Seriously, reread your question and consider if it's understandable. We are not clairvoyant.

'They' say there's no bad questions... 'They' didn't see this one, I guess.

I have edited and added details.

 

[phinds]

Given the exact drawing you have presented, the 10v reading does not make any sense, BUT ... without context, it is impossible to say that the drawing does or does not represent the "normal" assumption that the negative side of a power source is connected to ground.

If it is indeed a battery, then no connection to ground should be assumed and, as I said, the 10v reading would make no sense since the connection to ground is not part of any complete circuit and therefore has no current flowing through it.

 

[DaveE]

Given the exact drawing you have presented, the 10v reading does not make any sense, BUT ... without context, it is impossible to say that the drawing does or does not represent the "normal" assumption that the negative side of a power source is connected to ground.

If it is indeed a battery, then no connection to ground should be assumed and, as I said, the 10v reading would make no sense since the connection to ground is not part of any complete circuit and therefore has no current flowing through it.

The ground symbol in schematics is an arbitrary name for a circuit node. If there is only one drawn then it is meaningless.

 

[DaveE]

I have edited and added details.

Excellent, thank you!

The battery will cause current to flow through the resistors. Each resistor will have a voltage drop across it according to Ohm's law. Kirchhoff's voltage law says that the voltages around any loop must sum to zero. Your voltmeter isn't measuring just the battery voltage, it's measuring the battery voltage minus the voltage across R3, which, by KVL, is also equal to the sum of the voltages across R1 and R2. This circuit is often called a "voltage divider", if you want to search for more info.

So,
step 1 : What is the current flowing around that circuit loop?
step 2 : What is the voltage across each of the resistors due to that current flow?

There are some excellent tutorial videos at Khan Academy, check those out.

 

[phinds]

@DaveE, I am confused. You show skepticism of my reply and then you give the same reply. Huh?

 

[DaveE]

@DaveE, I am confused. You show skepticism of my reply and then you give the same reply. Huh?

Sorry, I misunderstood your reply, I think. I'll undo it.
"the same reply"... Not exactly.

 

[sophiecentaur]

I have edited and added details.

I can't see any points A and B . . . . . yet.

Voltage is Potential Difference; the difference on potential between two points. Any chosen point on a circuit has no 'Volts' until referred to another point.

 

[phinds]

I can't see any points A and B . . . . . yet.

Voltage is Potential Difference; the difference on potential between two points. Any chosen point on a circuit has no 'Volts' until referred to another point.

I think that's covered by

but why is the voltmeter reading not equal to 10 volts

 

[sophiecentaur]

I think that's covered by

Some things require a lot of repetition. water dripping on a stone.