MH's ideal coil and voltage question

[minnie]

   Come on tinman, the answer's in the question.
            John.

[Magneticitist]

the time constant for the inductor is based upon the concept that an inductor can never actually reach infinity, but never actually has a 'maximum' throttle. it just starts to become too difficult to distinguish the differences between the mathematical volumes of natural logarithm after the 5th time constant.

this does not help the hypothetical non resistant coil situation supplied with an infinite current/voltage ratio.

I personally do not quite understand the initial question as it seems vague, or I simply am not interpreting it properly being that as Brad said these types of exercises usually involve a series resistance. MH has made it clear a resistance is not required to run the test but even if our coil reaches a discernible infinity limit in 20 seconds that still doesn't change the basic principle of the question Brad has an issue with, the general idea of a proposed ideal voltage source meeting a proposed 0 resistance conductor, and substituting R=0 with R=1.

[tinman]

   Come on tinman, the answer's in the question.
            John.

The answer is not in the question,as the question is based around an inductor that dose not exist,and a voltage source that also dose not exist--that being the !!ideal! part of the question.
There for,the answer to this question will only be a theoretical answer,as the circuit cannot be tested to obtain the correct answer.

I dont think MH gave much thought to his question,or the outcome of installing the !ideal! parts to this !so called! simple circuit. As soon as you add things that do not exist,the question becomes far from simple,as there are no results obtained from such a circuit in test before.
It's much the same as those that theorize that anything that travels at the speed of light,will have infinite mass--a theory that !as yet! cannot be backed up by a practical test. Light travels at the speed of light,and it dose not have infinite mass .

So when i say that you cannot hook an ideal voltage across an ideal coil,you actually cannot do it,as both the ideal coil and ideal voltage do not exist,so i am technically correct.

Then comes the theoretical conundrum of trying to work out the question.

MH states that there is no time constant for current rise within the inductor,and i agree on this. But here is the conundrum.
The time constant is either 0 or infinite for maximum current flow through the inductor at T=0-->the moment the ideal voltage is placed across the ideal coil.
If the time constant is 0,that means that the current through the ideal inductor will rise instantly to an infinite value--as we have an ideal voltage source across the ideal inductor.
If the time constant is infinite for maximum current through the ideal inductor,then that means that no current flows through the inductor--ever,because if it takes an infinite amount of time to reach maximum current flow through the coil,then it also takes an infinite amount of time to reach a 10% value of maximum current flow through the ideal inductor,and it takes an infinite amount of time to reach 1% of the maximum amount of current flow through the ideal inductor--and so on. So it will take an infinite amount of time before current even starts to flow--so there will never be any current flow through the ideal inductor.

Now here comes the conundrum part. The ideal inductor has no resistance,and so now our ideal voltage is placed across a dead short,and that means an infinite amount of current will flow instantly.
At T=0,an ideal voltage of 4 volts is placed across the ideal inductor,for a period of 3 second's.
Either way you look at it,this is something that cannot happen--as i have stated many times now in my answer to the question.

The next problem is this.
I can claim my answer to be correct,and no one can disprove it,as the ideal inductor and ideal voltage source do not exist.
MH could say his answer is correct,and i could not prove it to be wrong,as i have no way of testing his theory.
MH stated that the question is not a trick question,but based on the fact that he is using an inductor that dose not exist,being supplied a voltage from a source that also dose not exist,how is any body to answer the question correctly,when such a circuit cannot be tested?.


Brad

[minnie]

  Just answer the question.

[tinman]

Brad,

Here are two small but significant hints:



2) MH's question is regarding what happens at t=0, i.e. the instant the Vsource is connected (MH, please confirm).

1) brush up on what it means mathematically when any number is divided by 0 (don't assume you are correct, verify it).

The only time 0 is used as a divisional number(that im aware of),is in computer arithmetic. But even then,it must be assigned with either a + or- value,and even then,the resultant value of the division is either negative infinity,or positive infinity.

There are no other cases i know of,or could find,where anything can be divided by 0,and result in a defined number or amount. Every attempt at explaining  that a number remains unchanged when divided by zero failed.


Brad