1

Physics, Astronomy & Cosmology / Gas discharge tube hydrogen

« on: 16/03/2024 04:06:10 »

In the gas discharge tube experiment for H2,  we have four emission lines in the visible spectrum. The explanation is that they are due to excited electrons that radiating according to the
formula:1/λ = R(1/nf? - 1/ni?) for nf= 2, ni = 3,4,5,6.

But QM requires that the electrons could only be excited by the exact frequency light (red, blue, violet, violet) in order to reradiate the four colors. But the source of the energy to the discharge tube is electrical, so how in the first place could the electrons get excited and reradiate. There are no visible light entering the discharge tube in the first place.   

2

New Theories / Can an atom absorb a photon, yet its total kinetic energy is decreased.

« on: 04/10/2023 15:09:39 »

Let's assume an atom consists of the nucleus and electrons as point particles. Take the inertial frame to be that of the fixed laboratory. Its total energy consists of the total kinetic and potential energy of the system of particles.If an electron absorbs a photon of energy E, the total energy of the atom increases by E. Can it happen that this increase in energy result in an increase of its total potential energy = E + Del(potential energy) and its total kinetic energy decreases by Del(potential energy).   

3

Physics, Astronomy & Cosmology / What em radiation frequencies can solid material blocks?

« on: 26/09/2023 20:12:02 »

What em radiation frequencies can solid material blocks:
1) metal.
2) non-metals

4

Physics, Astronomy & Cosmology / Working of IR Laser

« on: 26/06/2023 20:56:09 »

Hello,

Nd:YAG (neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12) is a crystal that is used as a lasing medium for solid-state lasers.

A "typical" laser has one end coated HR - highly reflective and the other end partial reflective. In the description of a company product for Nd:YAG laser rod, the ends are coated AR@1064nm/AR@1064nm. AR means anti-reflective. Can lasing occur in such a laser rod if we just shine some appropriate flashtube at it just like with a ruby laser rod.
 

5

Physics, Astronomy & Cosmology / How a photon is absorbed by matter.

« on: 02/04/2023 00:19:44 »

Say a photon of a certain frequency hits a piece of metal or non-conductor and it is absorbed:
1) what is the physical mechanism?
2) where will the energy go to?

6

Chemistry / Can glucose be synthesized without organic inputs as sources?

« on: 11/03/2023 23:59:35 »

Answer seems Yes. Synthesis without organic inputs.

Nature Magazine, 1887.
https://www.nature.com/articles/037007b0

"ANOTHER important acquisition to our store of knowledge has recently been made. Glucose, commonly called grape-sugar, has been artificially prepared by Drs. Emil Fischer and Julius Tafel in the chemical laboratory of the University of Würzburg."

What is the latest development. Is this synthetic glucose considered a "food", digestible.

7

Physics, Astronomy & Cosmology / Free fall of charged particles (Attn: Hamdani Yosuf)

« on: 15/01/2023 16:40:30 »

It seems no one has done any free fall experiments for charged particles like electron, proton, charged ions. I'll like to seek the attention of Hamdani Yusuf as he posted some  comments about single photon experiments.

I'll like to know if it is possible to design an experiment to determine the free fall, say of a single electron in vacuum. Let's say we don't need high accuracy, just 15% accuracy. We create a high vacuum cylindrical chamber made of concrete/ceramic diameter 2m, height 5m. We try to eliminate electrical disturbance somehow and drop a single electron from the top middle of the chamber hoping any electrical disturbances would be minimized as the electron may be "far" from the surface of the chamber sides.

Is such an experiment possible? Is there a way to time the free fall of such an electron? 

8

Physics, Astronomy & Cosmology / How are standard masses being made with new SI definition?

« on: 12/01/2023 10:09:18 »

We now (May 2019) have a new SI definition of the base unit of the kilogram. How is one kilogram standard mass being calibrated? Who now issues such mass standards?

9

Chemistry / In what fundamental forms are energy released when hydrogen burns in oxygen?

« on: 18/06/2022 16:32:23 »

I have searched the internet all over and cannot get what I want. It just say things like... chemical energy is released as heat like in burning. Everyone knows that! But what is heat?

Take the burning of hydrogen in oxygen to water, in a closed vessel with nothing else:
1) Are there tables of values where we could calculate the amount of energy released?
2) In what exact form is energy released, say kinetic energy, potential energy, photon; don't just mention heat unless you tell what is heat and who gets the heat. If kinetic energy, then it must be the kinetic energy of the molecules of water.   

10

Physics, Astronomy & Cosmology / How can I pass a large DC current through mercury?

« on: 22/05/2022 16:17:33 »

If I apply a DC 5V voltage across a narrow column of mercury 1cm x 1cm x 0.5m, the current is about 1000 A. How can such an experiment be done at home. Our home supply cannot allow drawing such large a current; the power supply will trip. 

11

Chemistry / Will a water and diesel mix decompose at 500 degrees Celsius?

« on: 06/04/2022 11:11:33 »

Can we heat water/diesel to 500 deg C in a strong closed steel chamber(oxygen free or fully filled with water/diesel) without decomposition to constituent elements.

12

Physics, Astronomy & Cosmology / Graneau mercury fountain experiment.

« on: 15/12/2021 05:15:33 »

Google search will lead to the passage in "Newtonian Electrodynamics" which explains this experiment. It is associated with verifying if there is any Ampere's longitudinal forces between collinear elements in a conducting wire.

There are two electrodes connected to a high voltage DC source. One is a vertical copper rod bar; above this is a horizontally placed copper circular ring electrode of much larger radius. The electrodes are placed in a dielectric (insulator) container of mercury just covering the ring. When a DC source is connected to the electrodes, a  high current flows in the mercury. A mercury fountain will form with the mercury pushing up the middle of the ring and bulging up, overflowing back to the side of the ring.

I find it strange that the experimenter, Peter Graneau, did not mention if the mercury fountain will form independent of current direction. My understanding is that such experiments are usually current direction independent; it should work even with AC source. But I prefer a real confirmation. My google search finds nothing.

Anyone here "knows" the answer? Or better in doing a google search?
[EDITED]

13

Physics, Astronomy & Cosmology / Does the primary winding of a power substation step down transformer need ground

« on: 14/12/2021 08:05:18 »

I assume the single phase substation taps power from one of the 3-phase transmission line. One terminal of the primary connects to the transmission line. Does the other terminal need to be earthed ?

14

Physics, Astronomy & Cosmology / Can a 1m x 1m parallel plate capacitor be charged safely to 300 kV?

« on: 17/09/2020 15:41:18 »

I have a parallel plate capacitor 1 m x 1 m that is to be fully charged to 300 kV. The distance between the metal plates is 3 mm; the inner surface of one plate is to be coated with 1 mm ceramic (permittivity >=1000) leaving an air gap of 2 mm.   
1) Can such a capacitor be charged to 300 kV without dielectric failure.
2) Is there ways to experimentally measure the charge by discharging the the fully charged capacitor. Is such a method common practice. The accuracy needed is only about 5%.
3) Would a good experimental physicist be able to work with such a capacitor.
4) would there be significant charge leakage if left for 2 hr.

15

Physics, Astronomy & Cosmology / How is light speed related to refractive index?

« on: 02/08/2020 10:40:00 »

Refractive index of a medium is defined as : n = c / v; v is speed of light in medium.

I believe n is never measured directly as here is no way to directly verify c / v. So what I guess is that all refractive index values are  measured using n = sin α₁ / sin α₂. But then there is circular logic here. So Snell's law and n = c / v is just a hypothesis which is not experimentally verified.   

16

Physics, Astronomy & Cosmology / Can I assume that Coulomb's law applies in water?

« on: 21/02/2020 10:55:02 »

1) Can I assume that Coulombs law applies in water by replacing the the ε₀ for vacuum with
ε_water= ε₀ * water-dielectric-constant (about 80).
2) If 1) is true, what is the force between 2 charges +Q, +Q on the opposite surface of a water tank (assume ideal conditions) with separation d.

Thinker.

17

Physics, Astronomy & Cosmology / What is meant by "gamma energies"?

« on: 30/07/2019 11:43:33 »

What is meant by "gamma energies" in Compton scattering experiment using gamma rays. 

Energy calibration:
"A number of plastic disk sources of known gamma energies are supplied. Determining the
peak channel numbers for these known energies allows calibration of the equipment."

Energy (KeV)
Na-22, 511
Mn-54, 835
Co-57, 122

1) Does it mean the frequencies of the gamma rays could be obtained using: E=hf; f=E/h
2) If the frequency of the rays (e.g. Na-22) are measured directly with an instrument, would it give the same as f = E/h ?
3) What technique is there to directly measure frequency or wavelength?

18

General Science / Is there a neutral line from power stations?

« on: 23/07/2019 17:33:25 »

from internet:
"The power plant produces three different phases of AC power simultaneously, and the three phases are offset 120 degrees from each other. There are four wires coming out of every power plant: the three phases plus a neutral or ground common to all three..."
And then it says the neutral wire is connected to the ground.
 
My question now is how many conductor wires are there in overhead lines if the power station carries power through overhead lines.

19

Physics, Astronomy & Cosmology / photon violates energy conservation?

« on: 20/07/2019 17:42:43 »

Let's assume an atom A emits a photon of energy E₁ = hγ₁. The photon is absorbed by another atom B moving with a velocity relative to A. Because of the Doppler effect, the frequency of the absorbed photon is γ₂ where γ₁ != γ₂. This means the absorbed energy is E₂ = hγ₂ and E₁ != E₂. This implies a violation of energy conservation.

Where is the error?   

20

Physics, Astronomy & Cosmology / How fast are the electrons moving during beta decay?

« on: 05/05/2019 17:22:34 »

It is well known that the energy spectrum of the beta-decay electron is continuous; it was confirmed by the Ellis and Wooster 1927 experiment. It means the electron are ejected with speeds that may vary from zero to a maximum.

To date, are there any experiments done to directly measure the speed of the ejected beta electrons through the time-of-flight method? Can someone provide some links.