# Jacques

Senior Members

562

1. ## Tsolkas or Einstein ?

Read the wiki description of a Gyroscope I must complete my assertion by adding: The gyro won't settles in position P2 but continue to rotate in the inverse direction of the chamber rotation in the reference frame of the chamber. Do an experiment by yourself take a 3 axes gyro like that in you hand and rotate on your self. You will see that relative to your hand the gyro will rotate in the opposite direction that you rotate on yourself.
2. ## Voltage and ionization

The ionization energy of H is 13.6 eV With that information how can I estimate the volage I need to apply to 2 electrode in a H gas in order to get H+ ions ? What is happening to the electrons ? Can I get 100% of the H atom ionized? Thanks
3. ## Volt and electronvolt

I have something else bugging me. The force felt by the charge particle is proportionnal to the charge of the particle and the charge of the plate: $\vec{F} = \frac{Q_1Q_2}{4\pi\varepsilon_0 r^2}$ The number of charges on the plate depend on the capacity of the two plates. If I cut the plates in half and apply the same voltage, there will be half the charge so the force should be half of what it was. But E=qV, the energy is the same. How come what wrong in my reasonning Thanks
4. ## Tsolkas or Einstein ?

Even the thought experiment is wrong. The gyro won't settles in position P2 but continue to rotate in the inverse direction of the chamber rotation.

6. ## Volt and electronvolt

Thanks Swanson. That is what I expected, but was not sure. What was mixing up was the fact that the proton will undergo a smaller acceleration because of the mass, but for a much more long time. So the proton will move 1820 time slower than the electron ? An alpha particle 1/4 the proton speed ? An other question: If I increase the voltage between the plate, is there a voltage where electron will get off the negative plate. I know the vacuum tube diode, where cathode is heated to emit electron. But without heating will it happen ? If yes coating the cathode with a dielectric ceramic stop electron leaking from the cathode ?
7. ## Volt and electronvolt

I need to understand the relation between volt (V) and electronvolt (eV) in a system with particle and electric field. Let say that we have 2 larges plates in a vacuum and two test charged particle a proton and an electron. The distance between the plates is 1 meter. The electric potential between the plates is 100 volt and the charge of the particles are +1 and -1 elementary charge. If the plate are large enought the electric field gradian is constant in the middle betwen the plate. An electron at the negative plate will experience a force toward positive plate. I am tempted to tell that the electron will have an energy of 100 eV when it hit the positive plate. Is it right ??? Next if I do the inverse with the proton I am tempted to multiply with the proton_mass/electron_mass factor that give around 182,000 eV... That make no sense.?? The proton is 1820 more massive than the electron the magnitude of the charge is the same so the force exerted on them is the same but opposite direction. The electron being lighter will cross the gap a lot faster than the proton. The proton will accelerate less but for a longer time. That where I am lost and cannot find an answer to the question : how do you calculate the voltage needed to bring a particle to a chosen energy ?:confused:
8. ## Telescopes.

First not all telescopes revert the image: The galilean telescope doesn't invert the image. It is made with a convex objective lens and a concave ocular lens. That kind of telescope is very limited in magnification and are sometime used in theater binocular, no need for heavy prisms to revert the image back. But for more powerfull scope the occular is also a convex lens. If do some raytracing, you will understand why the image is inverted. raytracing applet Most of the time, refracting telescope have a little mirror or prism before the objective that revert back the up and down but not the left and right.
9. ## What the heck is that thing next to the Moon???

My guest is that it is Antares (alpha scorpio)
10. ## comets

The main accepted view is that earth water comes from comets impact, because of the hydrogen and deuterium ratio is the same as the comets, but some have other explaination This word applies to life seeding material comming from space. Just need a mixture of H and O and a spark.
11. ## Relative Ages of Galaxies

R.A. mean Right Ascension. It is used in the coordinate system used by astronomer. R.A. and Dec (declination) is like longitude and latitude. R.A. unit are hour, minute second and correspond to longitude. 24 hour R.A. is egal to 360 degree. Nothing to do with age
12. ## Really basic electronic question

I think that the part you are missing is you have a power source. The voltage would drop to zero fast if there were no current source. The voltage is maintain by the current source. The difference in potential energy use by different resistor depend on the current that goes throug each. The higher the resistance the less current goes throught. PS if the current source is not powerfull enough the voltage will drop.
13. ## Pesky Neutrons

I found that paper very interesting. It give an overview of the problems with fusion The Trouble With Fusion
14. ## Colour?

The art answer is also no. From the point of view of an artist black is the absence of color or a shade.
15. ## Pesky Neutrons

From wiki :Aneutronic
16. ## Electrostatic oscillator

The field would look like that I guess. I found a free program to trace electric field Electric Field It is 2D but it is free. I would like to find something similar in 3D I putted some charge but I am not sure if they are the best... Will there be an appreciable damping of the oscillation caused by EM radiotion of the charged particle? What are the factor causing the damping ?Thanks
17. ## Electrostatic oscillator

OK Does that mean that in linear accelerator you need magnet to keep the beam focused ? Just electrostatic wouldn't be enaught to keep the beam together. For the charging, that what I was expecting. Do you know if there are free electrostatic simulation program ? Thanks
18. ## Electrostatic oscillator

Hi Swansont Thanks for the answer but I figure out that I don't have time to figure out all the maths (family, work, girl friend...) but I will try to give what I know. The force on S is the summation of all forces between S and all elements of O. That will give the total force in the z direction since the force in xy plane all cancel out. That force will make S move toward the origin and the force will increase (because of the inverse square law) so need to intergrate over t also. that about it . I can see that a charge particle will oscillate. That bring me to an other question : If the particle have x and/or y different from zero but smaller than the ring, will the particle oscillate or will it hit the ring ? Also, how can we charge a non conductor ? Thanks
19. ## Electrostatic oscillator

Hi I have a question about some theorical setup and try to understand how it will behave. The goal of that exercise is to help me acquire some knowledge of how to apply the electromagnetism math to concrete setup. All setup are in empty space (no air) where gravity is negligible, in a farady cage and magnetically sheilded. First set up made up with 2 non-conducting objects. - A point like sphere S of charge Q1 and mass m1 - A perfect ring O of charge Q2 and radius R and mass m2 The center of O is at the origin and lay on xy plane S is at a distance z on the z axis What will happen if we keep O stationary and let S go. It depend of the charge of Q1 and Q2. If they are the same S will be repelled by O. If they are opposed S will be attracted to O. The geometry of O will give an acceleration to S toward the O center. The potential energy will be transformed in kinetic energy until S pass the origin. After that S will decelerate and the kinetic energy will transformed in potential energy until the kinetic energy is 0. S will accelerate back to the origin etc etc. So S will oscillate on the z axis. What is the frequency of that system ??? Also accelerated charge produce radiation and the system will loose energy. What is the damping of this oscillator ??? Setup two: same as setup one but with O made of a conductor. That's where it will get complicated because the motion of S create a magnetic field that will induce an electric current in O that will create a magnetic field that will modify S motion... But let concetrate on the first problem. How:confused: do I start ?
20. ## Lunar Eclipse Question

The red color comes from all the earth sunsets. If you were on the moon at that moment you would see the night side of the earth circled by a red ring. You can see some hint of that on that photo:
21. ## Fusion and particle accelerator

Roger I understand Bussard Polywell, but what I am investigating is completly different. The polywell attract the ion to the center to make them collide. For that you create a virtual cathode from electron trapped in a magnetic field. To create the magnetic field I see that the polywell use a huge amount of energy: That mean a lot of watts!My design doesn't need any magnetic field just an electric field. The polywell work with ion colliding in the center and the recirculation of the ion if they don't collide. My guess is that most of the ion won't collide because of the density of the plasma. In my design, the collision of the accelerated ion with the solid boron wall maybe much higher, but I lack the knowledge to compute the collision rate. Anybody out there to help me ? What is the probability that an H+ ion colliding with a solid boron cristal fuse? Some ion will be simply reflacted, other will be deflected and lose their energy and some will fuse... Also my desing enable the fusion to take place on a big area so the temperature won't be so extreme. And from Colliding Beam Fusion Reactor Who is right? or both are right but I missed something...
22. ## Lunar eclipse

August 1st 2008 eclipse Other eclipses
23. ## Lunar eclipse

That one is super! (not from me:) And a lot of others there
24. ## Lunar eclipse

Hi Happy that many of you enjoyed the show! For those where the sky was covered I took some photos. Not easy whitout a tripod but here they are ! The first one was taken when it was partial. On the last one you can see saturn to left.
25. ## Lunar eclipse

To inform you if you have a clear night and live Europe or America a nice lunar eclipse will happen ! Lunar eclipse animation More details
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