# Tag Info

0

Parallel rays reflecting on a concave mirror do intersect at one point, the focus, if the mirror is a parabola (in 2d plane geometry) or paraboloid (in 3d space geometry).

0

If you adopt a photonic model where the photons are seen as little particles like gas particle then the following simple demonstration indicates : The fundamental principle of mechanics gives : $N\frac{\triangle p}{\triangle t}=pS_{yz}$ Where N is the number of photons inside the cavity, p the radiation pressure and ${\triangle p}$ the change of ...

1

This question is too broad. It involves ALL the objects in the universe which have a surface, i.e., everything. I'm going to avoid giving a lecture here. In some liquids and most gases the electronic structure of each individual atom or molecule is enough to describe their spectra. The "property" you are looking for in the case of solids is the band ...

0

Several answers here already talk in great detail about how electron orbitals affect if a photon will be absorbed or not, but this is not the whole story. The color from reflected radiation is indeed the only factor if the surface is completely flat and perfectly reflective, excluding the black-body radiation, but most surfaces are not. Take for example all ...

2

Noether's theorem states that there exists a conservation law for every continuous (in fact, differentiable) symmetry. Reflection is a discrete symmetry, so the theorem is not applicable here. But, in quantum mechanics, you have the parity operator $P$, that reflects the coordinates $$P\psi(\vec{r}) = \psi(-\vec{r})$$ Since $P^2 = I$, the operator $P$ has ...

1

Let's zoom in to your diagram a bit and draw in some extra angles: This should make it obvious why $E_x = E \cos\theta$ and $E_z = E\sin\theta$.

1

What if I say that the mirror doesn't flip left and right? You've heard it right the mirror doesn't do the flipping. As the above answers say the mirror shows what is right infront of it. It's you(we humans) who think it is flipping. Let me get this in detail Before we begin tell me , 'What makes you think that the mirror flips your left and right?' Or ...

1

Although the shortfalls of focusing more light on the array have been described, a similar question is why you would not mount mirrors to reflect sunlight toward the array only when the incident angle is well off normal. This might provide some of the advantage of tracking the angle of the sun during the day. I think in this case the placement and size of ...

3

This is entirely based on the way light interacts with the materials. Mirrors are made of materials particularly chosen because they reflect light without distorting it. Some materials might reflect a lot of light, but the light might (essentially) "bounce" around inside the material in such a way that it comes out at odd angles or with odd colorings in a ...

1

It's very simple: you're dealing with an huge number of photons and you just know where the flux of photons is going. You don't know where the single photon is going and which is its momentum. Also considers that, when the photon affect the surface, it is absorbed by the materials; after it is reemitted.

1

When you observe the reflection of light, you are dealing with a huge number of photons forming a beam with radius $\delta r$. Spot you see has non-zero dimension. So each photon has its own uncertainty in position. In addtion, since photons can vibrate around its propagation direction, they have uncertainty in momentum (vector quantity). (Remember that you ...

Top 50 recent answers are included