Simple, everyday science

[Bozo Erectus]

Ive read that our science is good at generating electricity and using it, but still hasnt come up with an explanation of what electricity actually is. What is it about electricity thats mysterious?

 

[El_Machinae]

It's like gravity is mysterious. We know what it does, but not why it does it.

 

[nonconformist]

Ive read that our science is good at generating electricity and using it, but still hasnt come up with an explanation of what electricity actually is. What is it about electricity thats mysterious?

It's more or less the use of the term "electricity" to blanket bomb everything of that branch of physics.

 

[Tenochtitlan]

Thats why Mechanics > Electricity

These electrical engineers claim to understand, but they only memorize everything. Series this; parallel that.

 

[nonconformist]

Thats why Mechanics > Electricity

These electrical engineers claim to understand, but they only memorize everything. Series this; parallel that.

I really hope you're joking.

 

[Truronian]

Whats so mysterious about electricity? Moving electrons. Or do you mean the mystery of why particles can be charged in the first place?

 

[nonconformist]

Whats so mysterious about electricity? Moving electrons. Or do you mean the mystery of why particles can be charged in the first place?

I think he means "what is electricity" in broad terms, where as you have described current.

 

[sanabas]

I appreciate your time.

What, exactly, is going in-between the gas and the rocket and pushing them apart? That's the crux of my confusion with your position. In the roller skate analogy, my arm is what's 'in between' me and my ball.

In my statement, the thing that's 'in between' the two atoms is the explosion from their reaction, or the energy from their excited states.

The 'arm' in a rocket is the flow of gas caused by the different pressures. In the roller skate analogy, the arm changes the momentum of the ball, and also changes the momentum of the person on the roller skates, so that the net momentum of the system doesn't change. In a rocket, the pressure differential causes the momentum of the gas to change, and therefore also changes the momentum of the rocket, so that the net momentum of the rocket + gas doesn't change. They're not pushing against each other, and nothing actually explodes. The net momentum of the entire system doesn't change, the difference in pressure caused by the rapid burning of fuel causes one part of the system to move in one direction, and therefore the rest of the system moves in the opposite direction.

If you're still having trouble visualising it, imagine being on roller skates, and blowing air out your mouth and/or holding an electric fan. It won't move you much, but it will move you in the opposite direction to the flow of air. A rocket works the same way, it just generates the airflow differently.

 

[Truronian]

So it is.

In which case is electricity not just the general name given to the kinetic energy associated with those moving electrons?

I took his question to mean how does the process work rather than its dictionary definition. Bozo, could you please explain?

 

[El_Machinae]

Electricity is also associated with the urge for electrons to move.

 

[Perfection]

Half right.

The main resistance to heat transfer is at the boundary between the solid and the fluid - the laminar boundary layer.

Here:You actually imply that conduction is the slow part - adding insulation to reduce the rate of conduction.

Insulation doesn't do this - it actually stops bulk convection by being an obstruction to fluid movement. Also, it provides another set of laminar layers that the heat must flow across from the fluid to the solid again.

Ah, I get your point. That makes more sense now. Insulation is designed with pockets for a reason. I neglected to think of that.

I think my misconception came from the fact that you can mathematically treat these layers in the exact way you can treat conducting materials.

 

[Perfection]

Nice, I was thinking of something more along the lines of an ellipse:

Where the red dots are the foci of the semi-ellipse at the top.

But both work.

I don't see how yours does. Could you explain why? I just got done with finals week and I don't want to bust out the nasty calculus.

Chemical energy?what does this mean when the field of biology using the word energy and then chemistry using the same word as well?is it because they both use the same method of describing what energy is?

Yes, all sciences have an equivalent understanding of what energy is. Energy is a conserved scaler quantity that has the ability to perform work.

Chemical energy in actuality is electric energy. Chemistry is the study of the electronic interactions of atoms with each other.

Can you really 'store' electricity? Or isnt it more like storing the potential to generate it?

It's difficult to get at what you are saying with your terminology. There are, however numerous ways to store electric potential energy.

 

[History_Buff]

Thats why Mechanics > Electricity

These electrical engineers claim to understand, but they only memorize everything. Series this; parallel that.

I'm not even an electrical engineer, but I understand. It's not very hard at all. Electricity can be generalized down to basic magnetism. Electrons all store intrinsic negative charge. Similar charges repel each other, so when you have lots of electrons are in one place, and there is a place with comparitively few for them to move to, they go there, this is current. Voltage is the amount of work you can make the moving electrons (current) actually do. From this, and basic knowlegde of Ohms law, you can figure out Kirchoff's laws (they are simple once someone explains them), and with that you can analyze any simple circuit. It's trickier when you throw in things like Inductors, Capacitors, Diodes, Op-Amps etc. but it's all the same process, same as Mechanics.

 

[Truronian]

I don't see how yours does. Could you explain why? I just got done with finals week and I don't want to bust out the nasty calculus.

Bear in mind my diagram isn't accurate, and it also may not work

I think:

Any ray eminating from the blue area will make an angle with the normal at the point on the ellipse that it hits which is greater than the angle the left focus makes with the normal. IIRC the angles that the foci make with the normal at any point are equal (one of the properties of an ellipse), which means the angle of reflection will also be greater than the angle the right focus makes with the normal. This will force the beam of light to enter the right hand semicircle, where it bounce around a bit then hit the ellipse, when the same argument applies (it will end up in the blue area). Hence no light can ever enter the black rectangle.

The one thing I haven't really considered is multiple reflections on the ellipse, but I don't think thsi is a factor.

 

[El_Machinae]

But the poster said that diffusion was in effect. I don't see how it's possible to design that room, since any reflection is actually a new light source.

 

[Truronian]

But the poster said that diffusion was in effect. I don't see how it's possible to design that room, since any reflection is actually a new light source.

But the reflections have to go in a specific direction, which depends on the angle of incidence.

 

[Ayatollah So]

correct. IIRC, [heat loss] is directly proportional to the fourth power of the difference in temperatures.

Only the radiative component. But convection (wind blowing across your walls and roof) and conduction (basement walls and floor to the ground) dominate over radiative heat loss from a house.

On the other hand if you live in a place that sees decent sun in the winter (unlike here in Michigan) you can get a lot of radiative heat transfer into your house with skylights or windows. Use double-paned, low-IR-emissivity glass.

 

[El_Machinae]

Hey, back onto the straw, I think I may have figured out what you were talking about. Here's a question to show if I understand.

The 40' drinker could pull water up the straw, as long as there is still water in the cup, right? Because the air pressure at ground level would still be 'pushing' down on the water surface at ground level. It's only once all the water is in the straw, that it gets tough, and the last bit is impossible. Am I right?

 

[El_Machinae]

But the reflections have to go in a specific direction, which depends on the angle of incidence.

Yes, but when a reflection 'reflects', the photons will spread, due to diffusion. They radiate out, it's not like photons travel in discreet lines.

 

[Truronian]

Yes, but when a reflection 'reflects', the photons will spread, due to diffusion. They radiate out, it's not like photons travel in discreet lines.

I don't think thats correct

If this was the case you would never be able to see your reflection in a mirror, as the same part of you would be reflected from several different places on the mirror (from your eyes perspective).