13 votes

Is there any material that blocks a static magnetic field?

Yes, there are several different ways to manipulate magnetic fields. One way to shield an area from a magnetic field is to place a highly ferrous material like iron next to the source of the magnetic ...
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  • 593
5 votes
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How is it possible electromagnets keep a heavy maglev train levitating without forcing anything metallic to be flinged away?

First off there are many different types of maglev prototypes out there each with their pros and cons. In fact some designs have the drawback of needing shielded compartments for people with ...
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  • 593
4 votes

Magnetic levitation

Paradoxically, maybe the home-sized magnetic levitation could be a narrow area, where superconducting solutions could be cheap. I explain, why. Although room-temperature superconductivity is a dream, ...
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  • 2,344
4 votes
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Do infrared heaters have a special blackbody radiation specturm?

The heater is often so hot that it glows red, so it also radiates some visible light. And with fine enough instruments one could also detect some emitted microwave noise. But the main part of the ...
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3 votes
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Can you use an electromagnet to break the connection of a permanent magnet?

These are called electropermanent magnets. Source: https://en.wikipedia.org/wiki/Electropermanent_magnet The control can either come from rotating one of the magnets, or by using a control coil. If ...
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3 votes

Generating practical power without an iron core, but with high RPM

the iron structure(s) inside a generator serve the purpose of minimizing flux leakage, which maximizes the utilization of the magnetic field in generating electricity. One of the ways in which they ...
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3 votes
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Quantifying Static Electricity Hazard with High Explosives

Static electricity is a major issue when handling or dealing with explosives. When blast holes are loaded with ANFO (ammonium nitrate fuel oil) as the main explosive, and a specific density of ANFO ...
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  • 9,527
3 votes
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Defining camera as a passive radar

Not really. Firstly the RA in RADAR stands for RAdio which covers significantly longer wavelengths than the visible light (an in some cases near infra-red) which cameras can detect. While light ...
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3 votes
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Protect equipment against electromagnetic radiation

There are 2 effects to look out for: Magnetic induction into wiring from e.g. coronal mass ejections. The electrical grid is already largely protected against these events. To protect equipment in ...
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  • 736
2 votes
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Some questions about liquid nitrogen cooling

Regarding questions 2 and 3, I think you need to look deeper in the chemistry, reactivity, and heat transfer characteristics of Nitrogen. 1) It is not a noble gas. It is reactive, and you benefit ...
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2 votes

why is the outside of an electromagnet not magnetic?

The strength of an electromagnet's field will typically be strongest on the inside of the coil (talking about a normal electromagnets). This is true for the geometry of the magnet you've shown in the ...
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2 votes

Why is the current that can be drawn from an electric generator constant?

That statement about the current being independent of speed is just plain wrong. This should be obvious by thinking about the limiting case. When the generator isn't spinning at all, it won't ...
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2 votes
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Why is the current that can be drawn from an electric generator constant?

The current that a generator can produce is limited by the wire used in its construction. At some current level, the I2R losses in the wire will cause excessive heating inside the generator, as well ...
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  • 6,759
2 votes

Can a wireless signal of sufficiently high energy damage a wireless transceiver?

Yes, but it's unlikely. Damage from other frequencies will be limited because typical receivers have a pre-select filter after the antenna to filter out other frequencies. In band signals pass through ...
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2 votes
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How to split mercury with a magnetic force?

It looks like it should work. It is a little more geometry specific than you are thinking, so I have modified your design below. It will require a reasonable amount of experimentation to perfect the ...
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  • 7,489
2 votes

Can a Foucault's current brake be used on the rails themselves to brake trains?

Yes they can and they are in use. Details on Wiki By Sebastian Terfloth User:Sese_Ingolstadt - Own work, CC BY-SA 3.0 A linear eddy current brake in a German ICE 3 high-speed train in action.
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2 votes

Magnetic treatment of hard water to prevent scale and corrosion? How does this work?

There's very little data available to evaluate these claims. The manufacturers tend to rely on anecdotal information and testimonials rather than hard data, and no-one else really has any incentive ...
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  • 1,012
2 votes

Building oscillating magnetic field circuit

To make sure the inductor will respond that fast, you need to solve for the size of the inductor (which will make your magnetic field) which will be resonant at 1000Hz when coupled with a capacitor of ...
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2 votes

Use magnetic levitation to lift a carousel capable of turning 9000lbs

This isn't a real answer, but I feel compelled to provide it. What you are suggesting is perhaps possible, but very, very complicated. You will need to hire experts to engineer a magnetic bearing of ...
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  • 840
2 votes
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Linear solenoid mount

Figure 1. An image search for "M3 clevis male" throws up a wheelbarrow-full of images. You could use a female thread version but would need to connect the them with a male stud and maybe ...
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  • 8,449
2 votes
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Does an iPhone on airplane mode continue to emit electromagnetic radiation field?

All electric and electronic devices emit EM waves as a matter of course because changing current flows will produce waves like a motor, clock, or pocket calculator. But then there are also devices ...
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  • 3,345
1 vote

Is there a motor design where a rotor gradually moves into a stator?

It’s a pointless design since all you do is decrease the amount of magnetic coupling between the rotor and stator. You may as well just reduce the current - it’ll have the same effect. You’d have to ...
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1 vote

Can magnetic stripes be read wirelessly with lasers or other technologies?

Reading a magnetic field with a laser or other light source will be "difficult" because light is not charged and it does not have its own magnetic field.... except it is electromagnetic radiation. I ...
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1 vote

Can a electromagnet find a tube underground?

Actually if you can run the wire through the tube there is a simpler method. Send a radio signal through the wire and use a detector tuned to that signal. This requires some specialized equipment ...
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1 vote

DC relay relation with resistance

You cannot determine the operating voltage of a coil in this way unfortunately. The simplest way I can think of to determine the voltage of an unmarked relay would be to connect it to and adjustable ...
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  • 1,608
1 vote

Cheapest way to produce 200-1000 pieces of 0.2 mm copper plates

Your "best" options would be waterjet or laser cutting as long as the cutting tolerances are acceptable for your design. There are virtually no tooling costs. You can make a 2D cad drawing and get ...
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  • 1,578
1 vote

Transistor and diode on induction cookware

An induction heater creates an oscillating magnetic field near the coil. The "mechanism" to damage an electronic component is that eddy currents are induced in the metal parts of the component. ...
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1 vote

A radar that is not an OTH detection distance

No. Stating the obvious, a line of sight (LOS) system won't detect things below the horizon. Now, if atmospheric conditions cause a waveguide effect, signals could propogate farther (and back), but ...
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