21

Physics, Astronomy & Cosmology / Re: How does static electricity work?

« on: 05/06/2020 03:18:31 »

It's true that some rock types like granite have low conductivity, and safety earth connections in granite country need alternative methods (eg relying more on the Neutral wire). But most rock types give reasonable protection.

That's beside the point. Whenever an electric circuit is grounded or a conductor is grounded it can't build up a charge. Try. It won't work. The earth is a charge sink. I used to be an electronics technician. That was when I was first acquainted with the subject. Every time I worked on an electronic device I always grounded the chassis. Not once in those years did I ever get zapped. You won't get sapped from a conductor which is conducted to ground with a conductor. - Just as the text said.

22

Physics, Astronomy & Cosmology / Re: How does static electricity work?

« on: 04/06/2020 22:56:21 »

Since the king of insulting has posted twice since I posted I assume he was insulting again so I choose not to see his posts. However I can guess where his confusion lies this time and its about the "direct physical connection" comments. Unfortunately online definitions are never perfect. But textbooks are.

From Physics for Scientists and Engineers with Modern Physics -- A Strategic Approach by Randall D. Knight, (2004), pages 793-94

Any object which is physically connected to the earth through a conductor is said to be grounded. The effect of being grounded is that the object shares any excess charge it has with the earth. But the earth is so enormous that any conductor attached to the earth will be completely discharged.
   The purpose of grounding objects such as circuits and appliances. is to prevent the build up of any charge on objects.

Whomever is saying otherwise is quite wrong. Ignore them!

23

Physics, Astronomy & Cosmology / Re: How does static electricity work?

« on: 04/06/2020 15:59:00 »

Since three of us have said it's grounded- and given reasons, perhaps you should look up the definition.

You just couldn't look it up, could you?  You may be a good chemist but you make a lousy physicist. Any physicist would know I am right.

Definition of electrically grounded

Grounding is a principle of electricity that sometimes puzzles homeowners. In essence, the grounding system in a residential wiring system serves a "backup" pathway that provides an alternate route for electrical current to follow back to "ground" in the case of a problem in the wiring system.

Also: https://en.wikipedia.org/wiki/Ground_(electricity)

A typical earthing electrode (left of gray pipe), consisting of a conductive rod driven into the ground, at a home in Australia. Most electrical codes specify that the insulation on protective earthing conductors must be a distinctive color (or color combination) not used for any other purpose.
In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth.

Wood is NOT an insulator and therefore is not an alternate route for electrical current. No  insulator is a direct physical connection to the earth

Physics is NOT voted upon. Leave the physics to the physicists, bc. Stick to what you know, not to what you have a warm fuzzy feeling for.

Do you want the definition from a physics text?

24

Physics, Astronomy & Cosmology / Re: How does static electricity work?

« on: 04/06/2020 14:05:07 »

The handle in fact is connected to the ground through the door .

That is incorrect. Please look up the definition of grounded.

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Physics, Astronomy & Cosmology / Re: How does static electricity work?

« on: 04/06/2020 01:46:17 »

The handle in fact is connected to the ground through the door .

Unless the door is metal and that metal as a conductor leading into the grown then its not grounded. Since your door is wooden then doorknob its not grounded. But still there there can be a spark between body and ground. Discharge doesn't only happen between a body and a grounded object.

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Physics, Astronomy & Cosmology / Re: How does static electricity work?

« on: 03/06/2020 12:14:49 »

I noticed that there is no shock when touching the door, also no conduction, because if I touch the door and directly afterwards I touch the handle I get a shock from the handle. So the handle really is isolated from ground by the door, so I don't understand why I get shocked.

Noting is connected to ground unless its connected by a conductor. And just because you don't see or hear it doesn't mean that charge isn't being transferred. On a cold winter day rub your feet along the ground and then touch the doorknob, then you'll get zapped.

27

Just Chat! / Looking for news of police murderer

« on: 30/05/2020 20:37:02 »

I heard that there was a man who told a women that she should leash her dog. She called the police and said that he threatened here. The police came and be\eat the man to death. Does anybody knw where I can find news of tis online?

28

Physics, Astronomy & Cosmology / Re: Is the speed of light constant?

« on: 30/05/2020 04:22:25 »

Interesting. Does this mean that the speed of light is affected by gravity? Or, alternatively, could it be interpreted that the building is measured to be a different height by the two different observers?

Yes. See; http://www.speed-light.info/speed_of_light_gravity.htm

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Physics, Astronomy & Cosmology / Re: Does gravity attract masses in space, or does it curve space between them?

« on: 27/05/2020 04:59:52 »

What might be an example of a uniform gravitational field?

Consider a sphere of uniform mass density. Now cut out a sphere inside whose center is offset from the sphere's center. The gravitational field inside will be uiniforrm.

The surface of a sphere  with all the mass at the centre?
[/quote]

30

Just Chat! / Re: New textbooks

« on: 26/05/2020 22:20:06 »

My copy of Modern Classical Physics: Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics just came. Wow, it sure is a thick book. It's over 1500 pages long and about 5 cm thick! Nice book so far. It covers a lot of subjects, too.

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Physics, Astronomy & Cosmology / Re: Does gravity attract masses in space, or does it curve space between them?

« on: 26/05/2020 11:24:09 »

[That is interesting.Could you expand on that at all?
How would a uniform gravitational field manifest its quality of producing no spacetime curvature?

There is no spacetime curvature in a uniform gravitational field. It's a myth that all gravity is a curvature in spacetime. Curved spacetime is the same thing as tidal forces and a uniform gravitational field has no tidal forces.

32

Just Chat! / Re: New textbooks

« on: 25/05/2020 23:21:30 »

These textbooks are available online. See

Modern Classical Physics: Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics by Kip S. Thorne and Roger D. Blandford,  (2017)
https://b-ok.cc/book/3638821/d31774

and

Relativistic Classical Mechanics and Electrodynamics by Martin Land and Lawrence P. Horwitz (2020)
https://b-ok.cc/book/5521840/1e1f6c

33

Just Chat! / Re: Is there a safe pill for temporary libido reduction?

« on: 24/05/2020 23:01:36 »

Thinking about ex-girl friends gives me the same reaction.

34

Just Chat! / Re: New textbooks

« on: 24/05/2020 22:59:39 »

Did you also buy a dictionary, by any chance?
"New test books"

It's responses like this that make  me block your posts.. I thought that this time you might have something constructive to say but I see I was wrong, you're merely sarcastic, which is the lowest form of humor.

35

Just Chat! / New textbooks

« on: 24/05/2020 19:55:38 »

There are two great new textbooks out that I decided to buy. They are

Modern Classical Physics: Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics by Kip S. Thorne and Roger D. Blandford,   (2017)
https://www.amazon.com/gp/product/0691159025/ref=ppx_yo_dt_b_asin_image_o01_s00?ie=UTF8&psc=1

and

Relativistic Classical Mechanics and Electrodynamics by Martin Land and Lawrence P. Horwitz (2020)
https://www.amazon.com/gp/product/1681737086/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1

The prices aren't that bad either. Each seems great for learning relativity.

36

Physics, Astronomy & Cosmology / Re: Do electromagnetic waves have a fixed speed?

« on: 23/05/2020 22:27:19 »

I have never quite forgiven Einstein  for abolishing the aether  I still have lingering doubts that some thing like it must exist

Why?

37

New Theories / Re: What is a photon ?

« on: 22/05/2020 12:16:03 »

Is there a minimum limit for photon's frequency? Can it be 0?

No. It can't be zero.

The em wave/photon is caused by the acceleration of the electrons, if there is no frequency there is no acceleration, hence no energy (E=hf).

An atom can emit photons and in QM there is no such thing as an electron acceleration

Is it possible to produce 1 microHertz photon? What about 1 nanoHertz? Is there any lower limit?

Sure its possible. What is a gigahertz in one frame can be a microhertz in another frame.

38

Physics, Astronomy & Cosmology / Re: Can ratios of acceleration give the R-N metric?

« on: 20/05/2020 15:31:13 »

Acceleration may be represented in different forms;
as a scalar
as a vector
as a tensor
A vector is four dimensional. The tensor is rank two.

Only 4-acceleration is a 4-vector. 3-acceleration is a 3-vectgor. And acceleration is a rank-1 vector, not a scalar or a tensor of higher rank.

Various forms of acceleration may be related as ratios.
A change of basis may also include a ratio of unit vectors.

Those statements are wrong. You didn't justify any of your claims here.

Can ratios of form and basis give the Reissner-Nordström metric?

No.

39

Physics, Astronomy & Cosmology / Re: How does 'the math' explain complicated physics theories

« on: 19/05/2020 18:16:57 »

Physicists like Brian Greene (Until the End of Time etc.)  in lectures, discussions online . frequently 'explain' concepts like string theory that have no experimental evidence by saying  it's all there in 'the math'.

I hate it when people say those things.

40

New Theories / Re: What is a photon ?

« on: 19/05/2020 05:25:37 »

For example, a battery is grounded on its negative terminal.

That is merely a matter of convention. On American cars the negative terminal is "grounded" by attaching the negative terminal of the battery to the cars frame. In some European cars its the opposite, i.e. positive terminal is set to ground. There is nothing sacred about either convention.