Question by ceecookie
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I think this is a good question to discuss, so I put it on the forum
It means a difference in potential.Originally posted by ceecookie:Hi there,another minor questions.I dont like to spam the forum with thread asking abt minor questions
What do u mean by Potential diff? question c to e
Suppose we let the potential at P be 24 V, the potential at R will thus be 0V. This is because the battery is in between, and thus cause a rise of potential of 24V from R to P (the line on the right).
Similarly, if we let potential at P be 28V, potential at R will then be 4V.
Thus, if we talk only about potential, there's not much significance.
The significance only comes when we talk about the potential difference, but it represents a difference in potential, no matter what value we assign P to be.
Ok, that was a bit more in depth. At O levels, you can see potential difference as the drop in potential across 2 pts. Eg, from P to Q, what is the voltage drop? To fully understand, you will need to understand Kirchoff's law, which should be explained in your textbook... -
This reminds me of a qns being commonly asked during prelims perhaps O lvls exams. Why do birds not get electrocuted when they fly onto those high overhead electrical cables which carry large amounts of current?Originally posted by eagle:I think this is a good question to discuss, so I put it on the forum
It means a difference in potential.
Suppose we let the potential at P be 24 V, the potential at R will thus be 0V. This is because the battery is in between, and thus cause a rise of potential of 24V from R to P (the line on the right).
Similarly, if we let potential at P be 28V, potential at R will then be 4V.
Thus, if we talk only about potential, there's not much significance.
The significance only comes when we talk about the potential difference, but it represents a difference in potential, no matter what value we assign P to be.
Ok, that was a bit more in depth. At O levels, you can see potential difference as the drop in potential across 2 pts. Eg, from P to Q, what is the voltage drop? To fully understand, you will need to understand Kirchoff's law, which should be explained in your textbook... -
They do not get electrocuted only if they land on the neutral wire. As they do not touch the live wire, they are not part of the electrical circuit and hence electricity does not flow through them.
Woe betide any bird which decides to put its beak on the neighbouring wire. -
err.... They do not get electrocuted if they land on the live wire too. That's because there's no potential difference between the 2 legs.Originally posted by teraexa:They do not get electrocuted only if they land on the neutral wire. As they do not touch the live wire, they are not part of the electrical circuit and hence electricity does not flow through them.
Woe betide any bird which decides to put its beak on the neighbouring wire.
A current only flows when there's a potential difference. -
Yup. I really like this qn that it first dawn upon me. At first, it makes me wonder how cum this is happening. lol.Originally posted by eagle:err.... They do not get electrocuted if they land on the live wire too. That's because there's no potential difference between the 2 legs.
A current only flows when there's a potential difference.
Phyiscs is interesting. -
Oh ya reminds me..whats the direction of the current?Electrons come out from positive or negative terminal?
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Electrons are negatively charged. Opposite charges attract. Thus, electrons come out of negative terminal and go to positive terminal.Originally posted by lpx88:Oh ya reminds me..whats the direction of the current?Electrons come out from positive or negative terminal? -
If u r just using fomular, potiential difference means voltage...
If u want to noe more, then u will need to imagine...
Why do we need to know the difference???
Coz, to understand the movement of all universal things...
For example,
Wind - Air will move from cold to hot
Committing suicide - Suicider will move from high ground to low ground
Current - Move from lower potiential ground to higher potiential ground
Human - Move from low paying job to high paying job
Still dont understand??? Stick to formular lor -
To add on, there's such a thing called electron drift velocity. It is the speed at which electrons move through the wire, and is usually <1 cm/s. The reason why it moves so slowly is because what you have learnt that metal is a lot of +ve ions in a sea of electrons is a wrong model. This will be learnt further in A levels or uni (not sure), or in physics olympiad/physics S.Originally posted by tanjun:Electrons are negatively charged. Opposite charges attract. Thus, electrons come out of negative terminal and go to positive terminal.
Why do electrical equipments start immediately when u turn on the switch? The main reason is because the electrons moving at the start caused other electrons to move by electrostatical repulsion, and this repulsive force is extremely fast. Hence, all the electrons in the wire will start moving at around the same time... This is a very simplified explanation by the way...
This is what I always advocate as last case scenario/last min revision tactic. But when you have the time, it's always good to understand things.Originally posted by ispyyy:If u r just using fomular, potiential difference means voltage...
If u want to noe more, then u will need to imagine...
Why do we need to know the difference???
Coz, to understand the movement of all universal things...
For example,
Wind - Air will move from cold to hot
Committing suicide - Suicider will move from high ground to low ground
Current - Move from lower potiential ground to higher potiential ground
Human - Move from low paying job to high paying job
Still dont understand??? Stick to formular lor -
Sry ah eagle i still don understand..y battery in btw that means rise of 24 v ah?
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in short, yesOriginally posted by lpx88:Sry ah eagle i still don understand..y battery in btw that means rise of 24 v ah?