I don t understand! Regarding full shielding and external shielding, the master must come in to help

In order to avoid the influence of the external electric field on the instrument and equipment, or in order to avoid the influence of the electric field of the electrical equipment on the outside world, a cavity conductor is used to cover the external electric field, so that the inside is not affected, and the electrical equipment does not affect the outside world, which is called electrostatic shielding. The shield of the cavity conductor that is not grounded is the outer shield, and the shield where the cavity conductor is grounded is the full shield. The cavity conductor is in electrostatic equilibrium in the external electric field, and the field strength inside it is always equal to zero.

Therefore, it is unlikely that the external electric field will have any effect on its internal space. If there is a charged body in the cavity conductor, an equal amount of induced charge will be generated on its inner surface when the electrostatic equilibrium. If the shell is not grounded, the outer surface will produce an induced charge of the same amount and the same number as the internal charged body, and the electric field of the induced charge will have an impact on the outside world.

If the shell is grounded, even if there is a charged body inside, the algebraic sum of the charge induced on the inner surface and the charge on the charged body is zero, and the induced charge generated on the outer surface flows into the ground through the ground wire. The outside world cannot affect the inside of the shell, and the influence of the internal charged body on the outside world is also eliminated, so this kind of shielding is called full shielding. In order to prevent the interference of external signals, electrostatic shielding is widely used in scientific and technological work.

For example, the metal cover on the outside of electronic instruments and equipment, the lead skin on the outside of communication cables, etc., are all shielding measures used to prevent external electric field interference.

This issue can be considered separately.

If a cavity conductor is placed in an electrostatic field, how is the electric field distributed in the cavity?

An electric charge is placed inside the cavity conductor, how is the electric field distributed in the cavity conductor cavity and outside the conductor?

I can only transfer to the country. No, you can immigrate to the U.S. to visit**.

Just go to us ...

Shielded wires are transmission wires that wrap the signal wires with a metal mesh braid. The braid layer is generally red copper or tinned copper, and the principle is grounded through the outer shielding layer, and the external interference signal can be introduced to the ground by the layer, so as to avoid the interference signal from entering the inner conductor and reduce the loss of the transmission signal.

The shield of the shield wire does not allow multiple points to be grounded, because different grounding points are always different, and there is a potential difference between the points. If multi-point grounding, the formation of current in the shielding layer, the formation of current on the wire, and the formation of interference on the signal line, not only can not play the role of shielding, but the introduction of interference, especially in the occasion of the inverter, the interference contains a variety of higher harmonic components, resulting in greater impact, should be paid special attention.

The double-layer shield mentioned here is actually insulated and isolated between the two layers of shielding. Otherwise, it's still a single shield.

Yes, the internal account is mainly to record the actual business of the company, reflecting the company's operating conditions, and the external account is for the tax bureau to see, for example, we sometimes do not invoice the other party, then we do not have to pay taxes on this income, it will be included in the internal account, and the external account is not reflected, if the tax bureau looks at your internal account, then you will know that you have evaded taxes.

The meaning is about the same, in fact, the actual operation is not as terrible as you think, and the tax bureau can't let you look at the internal accounts too absolutely.

The general business of the external account is to prepare statements, file tax returns, copy taxes, etc.; The internal accounts also need to prepare financial reports, but they are in accordance with internal rules.

Hehe, it's not wrong for you to understand it this way, the internal accounts are used internally, and if you let the tax bureau know that you have two sets of accounts, you will be fined. Generally, the external account is those accounts with invoices, and the things without invoices cannot be reflected in the external account but should be reflected in the internal account. Therefore, the internal accounts should be collected by themselves, and the tax bureau should not be discovered.

I didn't dare to ask this question on the Internet, fainted,

Why do you make friends with him, such a bad friend is not worth socializing, what causes him a psychological shadow, he is so cheap, there will be a psychological shadow? Weibo doesn't need to be blocked, unfollow, and then blocked, making bad friends and harming yourself.

To protect yourself, you should kill him.

Copy this MAC address, turn on the router's firewall, then turn on MAC address filtering, select Prohibit MAC addresses from accessing the network in the set list, set fixed IPs on all computers you know, turn on only the following IPs in the router and it's done, and there is no way to surf the Internet.

Copy its MAC address.

Adding it to Mac Filter is all it takes.

In fact, you can add your own address to the Mac filter and set it as an off-list host, and you're good to go.

Enter enter the browser address bar to enter the router background management, and the rest of the operation is done according to what the two upstairs said.

Kill the virus under DOS, press F8 to enter safe mode after booting, and turn off all self-starting items.

Let's reinstall the system.

Or there is a virus.

Reinstall the system.

Poisoned, no way.

Or is it the aging of the power supply?

I think it's poisoned.