# Experiment to show that current leads voltage by 90 degrees in capacitor (Using RC circuit and Oscilloscope)...

S

#### server

##### Guest
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A

C

##### Guest
yuenhonkeung@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A
Good video. I like the mention of the ground lead connection.

#### 袁漢強 Edward Yuen

##### Guest
On Monday, 17 August 2020 at 13:59:41 UTC+8, Cydrome Leader wrote:
yuenho...@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A
Good video. I like the mention of the ground lead connection.
Thanks!

C

##### Guest
????????? Edward Yuen <yuenhonkeung@gmail.com> wrote:
On Monday, 17 August 2020 at 13:59:41 UTC+8, Cydrome Leader wrote:
yuenho...@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A
Good video. I like the mention of the ground lead connection.
Thanks!
I get a good laugh out of half melted ground leads on oscilloscopes.

P

#### Phil Allison

##### Guest
On Monday, August 17, 2020 at 3:59:41 PM UTC+10, Cydrome Leader wrote:
yuenhonkeung@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A

Good video. I like the mention of the ground lead connection.
** If the presenter had simply used an analogue scope - he could have employed a Lissajous pattern to prove the fact is a few seconds.

In phase = diagonal line

45 degree shift ( -3db_) = ellipse.

90 degree = circle.

...... Phil

J

#### Jim Jackson

##### Guest
On 2020-09-10, Phil Allison <pallison49@gmail.com> wrote:
On Monday, August 17, 2020 at 3:59:41 PM UTC+10, Cydrome Leader wrote:
yuenhonkeung@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A

Good video. I like the mention of the ground lead connection.

** If the presenter had simply used an analogue scope - he could have employed a Lissajous pattern to prove the fact is a few seconds.

In phase = diagonal line

45 degree shift ( -3db_) = ellipse.

90 degree = circle.
Ah! the memories - back in school in the 1960\'s, baffling the physics
teacher by hooking up the sig. gens to not only the front X input but
the Y input at the back - and another on the Z input to get travelling
spots.

S

#### Sjouke Burry

##### Guest
On 11.09.20 21:34, Jim Jackson wrote:
On 2020-09-10, Phil Allison <pallison49@gmail.com> wrote:
On Monday, August 17, 2020 at 3:59:41 PM UTC+10, Cydrome Leader wrote:
yuenhonkeung@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A

Good video. I like the mention of the ground lead connection.

** If the presenter had simply used an analogue scope - he could have employed a Lissajous pattern to prove the fact is a few seconds.

In phase = diagonal line

45 degree shift ( -3db_) = ellipse.

90 degree = circle.

Ah! the memories - back in school in the 1960\'s, baffling the physics
teacher by hooking up the sig. gens to not only the front X input but
the Y input at the back - and another on the Z input to get travelling
spots.
Aaah! Those old times....
I used x,y input, to put text on a scope screen,
with 2 dao\'s from an ordinary 80-286 computer.
Worked fine.
just visit each point which needed licht,
movement from one point to the next, was fast enough
to only show as dark lines,

J

#### Jim Jackson

##### Guest
On 2020-09-11, Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:
On 11.09.20 21:34, Jim Jackson wrote:
On 2020-09-10, Phil Allison <pallison49@gmail.com> wrote:
On Monday, August 17, 2020 at 3:59:41 PM UTC+10, Cydrome Leader wrote:
yuenhonkeung@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A

Good video. I like the mention of the ground lead connection.

** If the presenter had simply used an analogue scope - he could have employed a Lissajous pattern to prove the fact is a few seconds.

In phase = diagonal line

45 degree shift ( -3db_) = ellipse.

90 degree = circle.

Ah! the memories - back in school in the 1960\'s, baffling the physics
teacher by hooking up the sig. gens to not only the front X input but
the Y input at the back - and another on the Z input to get travelling
spots.

Aaah! Those old times....
I used x,y input, to put text on a scope screen,
with 2 dao\'s from an ordinary 80-286 computer.
Worked fine.
Lovely - but in the late 1960\'s the school I was at didn\'t have a
computer

But back in the 40\'s scopes, well CRTs, were used as RAM for some of the
first progammable computers.

https://en.wikipedia.org/wiki/Williams_tube

just visit each point which needed licht,
movement from one point to the next, was fast enough
to only show as dark lines,

C

##### Guest
Jim Jackson <jj@franjam.org.uk> wrote:
On 2020-09-11, Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:
On 11.09.20 21:34, Jim Jackson wrote:
On 2020-09-10, Phil Allison <pallison49@gmail.com> wrote:
On Monday, August 17, 2020 at 3:59:41 PM UTC+10, Cydrome Leader wrote:
yuenhonkeung@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A

Good video. I like the mention of the ground lead connection.

** If the presenter had simply used an analogue scope - he could have employed a Lissajous pattern to prove the fact is a few seconds.

In phase = diagonal line

45 degree shift ( -3db_) = ellipse.

90 degree = circle.

Ah! the memories - back in school in the 1960\'s, baffling the physics
teacher by hooking up the sig. gens to not only the front X input but
the Y input at the back - and another on the Z input to get travelling
spots.

Aaah! Those old times....
I used x,y input, to put text on a scope screen,
with 2 dao\'s from an ordinary 80-286 computer.
Worked fine.

Lovely - but in the late 1960\'s the school I was at didn\'t have a
computer

But back in the 40\'s scopes, well CRTs, were used as RAM for some of the
first progammable computers.

https://en.wikipedia.org/wiki/Williams_tube

just visit each point which needed licht,
movement from one point to the next, was fast enough
to only show as dark lines,
When did they stop making those memory CRT tubes for scopes and raster
display for old computers?

C

##### Guest
Cydrome Leader <presence@mungepanix.com> wrote:
Jim Jackson <jj@franjam.org.uk> wrote:
On 2020-09-11, Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:
On 11.09.20 21:34, Jim Jackson wrote:
On 2020-09-10, Phil Allison <pallison49@gmail.com> wrote:
On Monday, August 17, 2020 at 3:59:41 PM UTC+10, Cydrome Leader wrote:
yuenhonkeung@gmail.com wrote:
Many books told me that current leads voltage by 90 degrees in capacitor.
So, I designed an experiment to show that it is true. You can do the experiment at home or in the laboratory.

Here is my experiment in youtube: https://www.youtube.com/watch?v=wjQsyLv0X7A

Good video. I like the mention of the ground lead connection.

** If the presenter had simply used an analogue scope - he could have employed a Lissajous pattern to prove the fact is a few seconds.

In phase = diagonal line

45 degree shift ( -3db_) = ellipse.

90 degree = circle.

Ah! the memories - back in school in the 1960\'s, baffling the physics
teacher by hooking up the sig. gens to not only the front X input but
the Y input at the back - and another on the Z input to get travelling
spots.

Aaah! Those old times....
I used x,y input, to put text on a scope screen,
with 2 dao\'s from an ordinary 80-286 computer.
Worked fine.

Lovely - but in the late 1960\'s the school I was at didn\'t have a
computer

But back in the 40\'s scopes, well CRTs, were used as RAM for some of the
first progammable computers.

https://en.wikipedia.org/wiki/Williams_tube

just visit each point which needed licht,
movement from one point to the next, was fast enough
to only show as dark lines,

When did they stop making those memory CRT tubes for scopes and raster
display for old computers?
correction, vector displays.