## Which is having more energy – Valence band or Conduction Band?

I want to know which band is having more energy? valence or conduction band?

The energy corresponding to conductionband is more than that of valence band.

The valence band is simply the outermost electron orbital of an atom of any specific material that electrons actually occupy.

The conduction band is the band of electron orbitals that electrons can jump up into from the valence band when excited.

## Maxwell’s equation in cylindrical coordinate system

What is the derivation of cylindrical Maxwell equations.

Maxwells equation in cylindrical coordinate system

Maxwell equation

## Big Bang and Dark Energy – A post by Jason George

Can you please help debunk my big bang theory that aims to answer issues the current model cannot? We assume dark energy is consistent because of our measurements of it are over a short time relative to an area with mass “evenly distributed over it”, But time and space are unified. We know the presence of mass slows the movement of time. The same should be true about the expansion/generation of space.

This is possibly confirmed by recent studies and is another discrepancy the current model fails to account for. https://www.scientificamerican.com/article/cosmic-speed-measurement-suggests-dark-energy-mystery/

https://chandra.si.edu/press/19_releases/press_012919.html

In an area lacking enough mass a spherical peak facing outward (the opposite direction a sphere of gravity points) would form where time and space are generated at an extremely high rate. Virtual quantum pairs would appear split around opposite sides of the peaks infinitesimal center and separate further around peak/sphere/center. They would do so at very quickly and be randomly distributed. This random distribution would leave an asymmetry in the amount of matter/anti-matter produced on opposite halves of the peak, flowing away from the peak that causes the dominant one on each half to annihilate the opposite near it leaving pockets of cmbr in space(from the annihilated particles) around pockets of quarks.) Different areas around the center would be dominated by the opposite after concurrent generations. This means either we are located somewhere in this initial dominant ring or in a successive area dominated by a large enough amount of matter, I’m not sure if this can ever be solved.

Virtual particles become actual particles the longer they are separated by an external force. Space would be spreading very quickly but would slow down as the mass was generated this is concurrent with what we know about the big bang. Lots of energy, lots of expansion. that slows rapidly. People will object to this theory because the universe has no center for a peak to form. every point in space that existed at t=0 was and still is an infinite peak where this process is still happening. The original points would be spreading away from each other so that their generated mass/space never meet but their cmbr does(because it moves at the speed of light, faster than the slowed generated space). The peaks themselves would not lower/slow because of the mass generated around them because ∞ minus any number =∞. This could also mean time has no beginning/an illusion, which might be more likely since we are assuming space is infinite too.

I don’t think there would be anyway to determine that in our observable universe. This might also explain what dark matter really is, if dark energies acceleration was relative to the mass in the area then the generated space around formed mass would have accelerated slower relatively to the gaps.

## HC Verma’s Lectures on Physics

Are you preparing for IIT JEE ?

These lectures will be very much useful for you in undersatnding the Basic concepts.

## What is the force which creates the jerk on our body when brakes are applied?

“What is the force which creates the jerk on our body when brakes are applied?” (Ab Waheed Ashraff asked)

When we are traveling in a vehicle and when brakes are applied suddenly, we feel a jerk. This is caused by inertia of motion of our body.

Inertia is the inherent property of every body by virtue of which resists any change in its state of rest or the state of uniform motion in a stratight line.

When we are on a moving bus, our body is moving with the same speed as the bus. When brakes are applied suddenly, our feet will come to rest along with the bus, but the upper body will tend to continue with the same speed as before due to its inertia of motion.. Thus we feel the jerk.

Fictitious force (Pseudo Force)

The case can also be explained on the basis of pseudoforce. When brakes are applied, there is a sudden deceleration. Now the frame of reference is not an inertial frame of reference; it is now a non-inertial frame of reference.

When a body is freely placed in such a system, though no net forces are directly acting on the body, it experiences and behaves as if a force is acting on it. The magnitude of this force is equal to the mass of the body multiplied by the acceleration of the frame of reference in the reverse direction.

Fictitious Force = – (mass of body) (acceleration of system)

The direction of pseudoforce will be opposite to the direction of acceleration of the frame of reference. In case of deceleration, the pseudo force will be in the direction of motion. So we feel a jerk in the direction of motion itself when brakes are applied.

PLEASE WATCH THIS LESSON FROM H C VERMA (The author of Concepts of Physics, the book referred by most of the students for preparation for IIT JEE)

## You can’t build a machine to clean up the mess of a previous machine!

I am not a student of physics as my question will likely reveal. I understand there is a principle in physics that you can’t build a machine to clean up the mess of a previous machine. I am wondering if this is an interpretation of the second law of thermodynamics or if it stems from someplace else?

The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible

The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible

Clausius statement

Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time.

Kelvin statements

It is impossible for a self-acting machine, unaided by any external agency, to convey heat from one body to another at a higher temperature.It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects

Planck’s proposition

It is impossible to construct an engine which will work in a complete cycle, and produce no effect except the raising of a weight and cooling of a heat reservoir

## Three blocks m 2m and 3m are tied with string and are moving with constant velocity linearly calculate tension

Three blocks m 2m and 3m are tied with string and are moving with constant velocity linearly calculate tension