Sorry to disillusion you academics, but it is in Nelcon and Parker, the
standard A level Physics Text book when I was at school - I have it here -
P.684 !
However I would add that if you increase the values, say to 100 Volts, and
10,000uF it is very clear what happens to the extra energy when you connect
the terminals ... "SPLAT !" is a good onomatopoeic term.
Is anybody going to be transmitting over the weekend ?
When might I hear some signals on 73 / 136 ?
73
Hugh M0WYE
----- Original Message -----
From: "Andy talbot" <[email protected]>
To: <[email protected]>
Sent: Friday, November 08, 2002 2:57 PM
Subject: RE: LF: To Ponder over the weekend
Can tell you come from a university background Jim, do you ask that of
applicants for courses at herts.ac?
I was asked exactly the same question when applying for Southampton Uni.
in
1976.
Andy G4JNT
-----Original Message-----
From: James Moritz [SMTP:[email protected]]
Sent: 2002/11/08 11:52
To: [email protected]
Subject: Re: LF: To Ponder over the weekend
Dear Andy, LF group,
At 09:38 08/11/2002 +0000, you wrote:
>This simple puzzle caused more discussion in my office this morning than
it
>had any right to....
Here is another conundrum along similar lines - you have two identical,
loss-free 1uF capacitors, one is charged to 10V, the other is discharged.
You then connect the two in parallel so the total C is now 2uF - charge
will flow from the charged capacitor into the discharged capacitor.
Assuming charge Q is conserved, and that Q=CV, the voltage must now be 5V.
But the stored energy in a capacitor =1/2CV^2, so with the single charged
capacitor, the stored energy is 1/2 x 1u x 100 = 50uJ, while with both
capacitors in parallel it is only 1/2 x 2u x 25 = 25uJ. So where has the
other 25uJ gone?
Cheers, Jim Moritz
73 de M0BMU
|
