What is the working principle of wire grid polarizers?

In summary, the conversation discusses doubts about the concept of current flowing inside a conductor and its relation to Maxwell's equations. It also questions the working principle of wire grid polarizers. The conversation concludes with one participant unable to answer the question about wire grid polarizers.
  • #1
allister
1
0
Hello forum,
I have a few doubts on EM.
1. The skin depth formula for constant current(DC) shows that there can be current uniformly distributed through the cross-section of a conductor.However as there can be no electric field within a conductor(as per Maxwell's equations) there can be no force on the electrons within a conductor and the electrons do not move inside the conductor and so there is no current inside a conductor.These two facts seem contradictory.
2. Also,if it is so that current flows inside a conductor,the drift velocity of electrons is too slow.Is it the EM wave on the periphery of the conductor that causes a bulb to light as soon as it is switched on?
3. I am a bit confused about the working principle of wire grid polarizers. Maxwell's equations says that there shall be a non zero magnetic field on the surface of a conductor as an EM wave is incident on it.That means there shall be a varying surface current density(i.e. motion of electrons).As those grids which have their grids parallel to the E vector allow that and thus satisfy Maxwell can reflect EM waves.Please correct me if I am wrong.

thanks
 
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  • #2
allister said:
Hello forum,
I have a few doubts on EM.
1. The skin depth formula for constant current(DC) shows that there can be current uniformly distributed through the cross-section of a conductor.However as there can be no electric field within a conductor(as per Maxwell's equations) there can be no force on the electrons within a conductor and the electrons do not move inside the conductor and so there is no current inside a conductor.These two facts seem contradictory.

I don't think this applies to an electronic circuit, as it isn't a static situation.

2. Also,if it is so that current flows inside a conductor,the drift velocity of electrons is too slow.Is it the EM wave on the periphery of the conductor that causes a bulb to light as soon as it is switched on?

The drift velocity of the electrons may be slow, but current flows throughout the circuit all at once. Consider turning on the hot water faucet in your kitchen sink. Water starts to flow out of the faucet immediately, but it takes a while for the water from the hot water heater to get through the pipes to the faucet, so you have to wait a bit to get hot water. Current is similar. The drift velocity is slow, but when you initially flip the switch you have current flowing everywhere, including through the bulb.

I can't answer number three, sorry.
 

1. What is skin effect?

The skin effect is a phenomenon in which alternating current (AC) tends to flow more on the surface of a conductor rather than through its entire cross section. This is due to the interaction between the AC electromagnetic field and the electrical resistance of the conductor, causing the current to concentrate near the surface.

2. How does skin effect affect the performance of electrical systems?

Skin effect can cause an increase in electrical resistance, leading to a decrease in efficiency and power transmission of electrical systems. This can result in power loss, increased heating, and decreased functionality, especially at high frequencies.

3. What are polarisers and how do they work?

Polarisers are devices that filter or "polarise" light waves by allowing only certain orientations of the electromagnetic field to pass through. They are made of materials that can selectively absorb or reflect light based on its polarization, thus creating a polarized output.

4. What are the applications of polarisers?

Polarisers have a wide range of applications, including in optical instruments such as cameras, microscopes, and telescopes. They are also used in LCD displays, sunglasses, and 3D glasses. In scientific research, polarisers are used to study the properties of light and its interactions with various materials.

5. Can skin effect impact the performance of polarisers?

Yes, skin effect can affect the performance of polarisers by causing distortions in the polarization of light passing through them. This can result in reduced accuracy and functionality in devices that rely on polarised light, such as cameras and LCD displays. Careful design and use of appropriate materials can help mitigate the effects of skin effect on polarisers.

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