using current to measure a time

[Andy Baxter]

John Fields said:

---
It seems to me that by your not cross-posting, by your off-handed
rejection of several solutions which have been presented to you,
and by not using in-line references, you're not really looking for a
solution to your "problem", but instead are more interested in
playing games.

I think he's been given a practical assignment in school physics /
electronics, but isn't sure how to do it, and doesn't really want to do
the experiment anyway.

To Panther - if you don't do the experiment, you're cheating yourself. The
whole of science is based on trying out your ideas against the real world
by testing them to see if they work, so if you don't do that bit, you're
not really learning science.

 

[Panther]

To Panther - if you don't do the experiment, you're cheating yourself. The

whole of science is based on trying out your ideas against the real world
by testing them to see if they work, so if you don't do that bit, you're
not really learning science.

Nononono

I am doing the practical it's just that i have ONE WEEK to do it in and if I
just measure the voltages then I won't have time to work out the time, so if
I could record the voltages and do the calculations later using some formula
it would bebetter.

 

[Panther]

It seems to me that by your not cross-posting, by your off-handed

rejection of several solutions which have been presented to you,
and by not using in-line references, you're not really looking for a
solution to your "problem", but instead are more interested in
playing games.

Am I wrong?

I'm sorry but I cannot do those complicated solutions, I am poor at
practicals/electronics. Simpler circuits are better.

 

[Andy Baxter]

Panther said:

Nononono

I am doing the practical it's just that i have ONE WEEK to do it in and if I
just measure the voltages then I won't have time to work out the time, so if
I could record the voltages and do the calculations later using some formula
it would bebetter.

It shouldn't take you long to work out the times - it's a simple formula.
Look up 'capacitor', 'exponential decay', and 'time constant' on google.

 

[Rich Grise]

I'm sorry but I cannot do those complicated solutions, I am poor at
practicals/electronics. Simpler circuits are better.

Then your best advice is to go back to school, but read the textbooks
this time. There are no simpler answers to your question if you refuse
to become educated in the methods and background involved.

The ball is in your court.

Good Luck!
Rich

 

[Rich Grise]

Nononono

I am doing the practical it's just that i have ONE WEEK to do it in and if I
just measure the voltages then I won't have time to work out the time, so if
I could record the voltages and do the calculations later using some formula
it would bebetter.

Well, record the damn voltages then!

Set up your thing, with a DC power supply and series resistor to the
swinging ball. Connect a capacitor from the stationary ball to ground.
Measure the voltage at the capacitor. Any ordinary DVM should be able
to do that - in the US, they're US$9.95. Write this voltage down. It
doesn't matter what it is, just write it down. Swing the ball. Measure the
voltage at the capacitor, QUICKLY! Write that number down.

Record the value of the resistor and capacitor in step 1, and use
the equation for a charging capacitor to find out how long they were
touching.

If I gave you any more detailed of an answer than that, I would be
doing your labwork for you, which is even worse than doing your
homework for you.

Get up off your dead butt and learn something.

If you only have a week left, and haven't by now learned the material,
then maybe you should get into politics or something.

Good Luck!
Rich

 

[Panther]

OK I will do that thanks.

But you should really be blaming the school, not me for the lack of time. We
were given the assignments about a week ago, and expected to think of
something in a few days. I get practically no help from the teacher anyway.
I had to wait for ONE HOUR FOURTY FIVE MINUTES to get help for FIVE minutes,
because the teacher has to run out somewhere. I hope the next year
coursework involves no practical.

 

[Andy Baxter]

Panther said:

OK I will do that thanks.

But you should really be blaming the school, not me for the lack of time. We
were given the assignments about a week ago, and expected to think of
something in a few days. I get practically no help from the teacher anyway.
I had to wait for ONE HOUR FOURTY FIVE MINUTES to get help for FIVE minutes,
because the teacher has to run out somewhere. I hope the next year
coursework involves no practical.

Good luck with it,

andy.