# Electronics: trying to understand grounding point

• Femme_physics
In summary, the conversation discusses understanding grounding points in relation to potential differences in a circuit. The participants also mention the importance of correctly defining and calculating voltage drops in the direction of the current flow. The concept of Kirchoff's Voltage Law is also mentioned.
Femme_physics
Gold Member
Sorry for jumping through topics, I just have an electronics test tomorrow and I want to see I fully understand grounding points.

## Homework Statement

So I made up this circuit and found its voltage drop at every point

http://img137.imageshack.us/img137/3352/volts1.jpg

Now if I set Vab = 0 (i.e. turn Vab to the grounding point), I'm trying to calculate the potential differences now, but my total potential difference between -10 and +10 is only 20v. I'm missing 10V somewhere!

http://img845.imageshack.us/img845/1601/volts2.jpg

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Grrrrrr

Does point mean sector? Vab is the potential difference between points a and b.

ehild

Does point mean sector? Vab is the potential difference between points a and b.

So you can't set a point = 0, only potential difference = 0?

Femme_physics said:
So you can't set a point = 0, only potential difference = 0?

No, you can only set a point to 0, not a potential difference. Vab is a potential difference, so you don't get to choose its value; the Universe chooses it. You can, however, choose the potential at either "a" or "b" to be whatever you want.

Maybe an analogy would help. The height difference (analogous to potential difference) between the top and bottom of Mount Everest is a set value. It is what it is; nature has decided its value, and you can't change it. However, you can arbitrarily define the bottom of Mount Everest to be at height=0, or height=-1000 m; the top of the mountain would then be at 8000 or 7000 m (assuming the mountain is 8000 m tall).

ideasrule said:
Maybe an analogy would help. The height difference (analogous to potential difference) between the top and bottom of Mount Everest is a set value. It is what it is; nature has decided its value, and you can't change it. However, you can arbitrarily define the bottom of Mount Everest to be at height=0, or height=-1000 m; the top of the mountain would then be at 8000 or 7000 m (assuming the mountain is 8000 m tall).

Good example.
And yes setting Vab to zero would be OK, only when the current between a and b is zero.

So no matter where I set my ground point, the potential difference between 2 points remains constant?

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Femme_physics said:
I presume that the answer to my question above this post is "yes", in this case setting b = 0 I should be all correct here:

Correct?

PS calculator watches ftw!

And yes, Va = 10.
However, Vc = -20.

Voltage still goes down in the direction of the current.
Or perhaps I should say, that current flows down the mountain of voltage, like a mountain stream. ;)

That clears up a lot, thanks! :)
And yes, Va = 10.
However, Vc = -20.

Voltage still goes down in the direction of the current.
Or perhaps I should say, that current flows down the mountain of voltage, like a mountain stream. ;)

I see, so I should've done

Vbc = Vb - Vc

And not

Vbc = Vc - Va

It's always the first minus the second, yes?

Femme_physics said:
I see, so I should've done

Vbc = Vb - Vc

And not

Vbc = Vc - Va

It's always the first minus the second, yes?

I guess so, but that would be mostly about how you define it yourself.
However you define or use it, make sure that voltage goes down in the direction of your current.

I like Serena said:
I guess so, but that would be mostly about how you define it yourself.
However you define or use it, make sure that voltage goes down in the direction of your current.

Makes perfect sense :) And, as it hit the source, it increases again, right?

Femme_physics said:
Makes perfect sense :) And, as it hit the source, it increases again, right?

Yep. Guaranteeing that KVL works! :)

I like Serena said:
Yep. Guaranteeing that KVL works! :)

Need...consume...more...science...knowledge.. *drools*

Thanks

Don't forget the item that increases your abilities!

## 1. What is a grounding point in electronics?

A grounding point is a point in an electrical circuit that is connected to the ground or earth. It serves as a reference point for the voltage in the circuit and helps to prevent electric shock and damage to electronic devices.

## 2. Why is a grounding point important in electronics?

A grounding point is important because it helps to protect both people and electronic devices from electric shock. It also helps to prevent damage to electronic devices by providing a safe path for excess electrical current to flow to the ground.

## 3. How is a grounding point established in an electronic circuit?

A grounding point is established by connecting a wire from the circuit to a metal rod that is inserted into the earth. This creates a low resistance path for excess electrical current to flow to the ground.

## 4. Can a grounding point be shared between multiple electronic devices?

Yes, a grounding point can be shared between multiple electronic devices as long as they are all connected to the same electrical circuit. This is often the case in homes and buildings where all the outlets are connected to the same grounding point.

## 5. What are the consequences of not having a grounding point in an electronic circuit?

Not having a grounding point in an electronic circuit can lead to electric shock, damage to electronic devices, and even electrical fires. Without a grounding point, excess electrical current has nowhere to go and can cause harm to both people and devices.

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