Hello,

I have a small doubt in Voltage divider network.

Below are the simple circuit, Of course the voltage will get divide equally at that voltage probe with respect to ground.


But I have got a doubt in the below circuit what will happen if i ground the middle point?
How the voltage is still getting divide equally ?

 

How much current will flow in each resistor?

If the bottom of R1 is at 0 V (which is all that the ground means), what will the voltage be at the top of it?

If the top of R2 is at 0 V (which is all that the ground means), what will the voltage be at the bottom of of it?

 

See
Why do not you use Spice?

 

See
Why do not you use Spice?

Perhaps he is hoping to understand what and why instead of just letting a program do his thinking for him and relying on the answers it provides without any understanding of why they are the way they are.

 

A common point (GND) is an abstraction, a conditional zero. This point, relative to which the circuit voltage is determined. This point is put where it is convenient. In the first scheme, the voltage divider is immediately visible, unlike the second one. Although the voltage across the resistors does not change.

 

Hello,

I have a small doubt in Voltage divider network.

Below are the simple circuit, Of course the voltage will get divide equally at that voltage probe with respect to ground.
View attachment 129839

But I have got a doubt in the below circuit what will happen if i ground the middle point?
How the voltage is still getting divide equally ?


View attachment 129840

Ground is only referenced to one terminal of the battery, so if your battery terminals are not connected to ground, no voltage will be measured.

 

second circuit IS NOT a divider

 

second circuit IS NOT a divider

The second circuit is still a voltage divider.

Think in terms of nodes.
You agree that the first circuit is a voltage divider. Adding the GND reference does nothing to the circuit except change the absolute values at each node measured with respect to a reference node (GND). The relative voltages remain the same.

In the first circuit,
A1 = +12V
A2 = +6V
A3 = 0V

In the second circuit:
B1 = +6V
B2 = 0V
B3 = -6V

 

second circuit IS NOT a divider

Sure it is. The only difference is what node is used as the reference.

No, you can't just throw the classic "voltage divider equation" at it because that equation only applies to a subset of voltage divider circuits that satisfy certain caveats. This is why it is important to understand the principles and not just be an equation monkey.

 

second circuit IS NOT a divider

But it is.
It divides the voltage into two halves, the positive half appearing at the top of R1 and the negative half appearing at the bottom of R2.

 

A simple voltage divider is not that simple after all.

Allen

 

Ground is only referenced to one terminal of the battery, so if your battery terminals are not connected to ground, no voltage will be measured.

Hogwash! You can use any node you want as your ground reference and in both circuits there is a ground reference. That establishes that voltage on that node as being 0 V.

 

A simple voltage divider is not that simple after all.

Allen

While I'm not aware of any definition anywhere, most people would probably consider a "simple" or "classical" voltage divider to be the first circuit the TS posted and anything else, including the second, to be a "general" voltage divider. In essence, any circuit that adheres to

Vout = Vin R1/(R1+R2)

would be a classic voltage divider.

 

Hogwash! You can use any node you want as your ground reference and in both circuits there is a ground reference. That establishes that voltage on that node as being 0 V.

Bollocks! you can only measure Voltages between battery terminals or power suppy terminals, if Non are connected to earth, then No Voltage will be measured between earth and the supply.

 

Bollocks! you can only measure Voltages between battery terminals or power suppy terminals, if Non are connected to earth, then No Voltage will be measured between earth and the supply.

Take a battery.

Connect two resistors in series to it as shown in the TS's first post.

Don't connect any thing to earth.

Take a voltmeter.

Connect the negative probe to the junction of the resistors.

Connect the positive probe to the positive terminal of the battery.

Does your meter read anything?

Your negative probe defines the reference node for that measurement.

You can measure voltage between ANY two points -- where does it say that you can ONLY measure voltages between battery or supply terminals. If the two points are floating relative to each other, then the voltmeter (unless it is sufficiently high impedance to be sensitive to EM noise effects) will make it so that they are no longer floating relative to each other by enforcing zero volts between those two points.