# Do magnets affect the flow of an electric current?

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I know it’s kind of a stupid question, but I have been thinking this for a while. Do magnets affect the electricity itself that flows inside a wire? For example, say I am charging my phone and it’s connected to a wall socket. If I placed a magnet in the middle of my charger wire (like literally on top of the wire) would the magnet stop the electricity from flowing since it’s getting attracted to the magnet? Would it have any effect at all on the flow of electrons inside the wire?

In: Physics

The short answer is no. Magnets can induce electricity into wires, but you would need a very large/strong magnet and move it over the wire repeatedly to get any effect at all.

Yes and no. Magnetism and electron flow (electricity) are inherently related, inseparable in fact, but not quite in the way you suggest.

In fact we use magnets a LOT in electronics – that charger has a transformer that works due to magnetism, the output uses induced magnetism to remover electrical spikes, etc.

In your case, the electrons are in a bidirectional flow in the cable, so more or less in balance, and the magnet is in a stable state when it’s sat there, so the influence is all balanced out and stable. Moving your magnet rapidly through a coil of wire will induce a voltage in the wire, though, which is how dynamos work.

Induced currents occur when there is relative motion between a conductor and a magnetic field. This means either the conductor can move, or the field can expand and contract across the conductor (as in the constantly changing AC field). Since the current in the wire past the charger transformer is DC (for all intent and purposes, not changing) and the magnet is not moving, there should be no effect. Theoretically speaking, if you were to move your magnet back and forth you could induce a voltage, but it would be incredibly small.

A changing magnetic field induces an electrical current in a conductor but a static magnetic field does not.

So you have an effect when you put the magnet there or remove it but not when it is there. The effect is minimal because both positive and negative conductors are very close together so the induced current in both will cancel each other out.

If you would cut the charger cables apart and move the wire apart the effect will be larger when you put it close to one wire but unlikely large enough too disturbed the charging because USB allows for a voltage range of 4.4 – 5.25 V and there is part to filter out small transient voltages.
For any significant effect, you need to turn the wire into a coil and move the magnet through the coils. Enough loops in the coil and a strong magnet that move fast could create a voltage that could kill the phone.

The combination of wires in coils and magnets where one part move is exactly how electrical generator and motors are constructed. Here is a [simple demonstration](https://www.youtube.com/watch?v=J9b0J29OzAU) where a battery is used so you use electricity to create motion and not the other way around.

For the purposes of your concern, not really. A *changing* magnetic field will create an electric field, and a *changing* electric field creates a magnetic field. But static fields don’t do much.

They don’t do zero. A static magnetic field can affect an electric current via the [Hall Effect](https://en.wikipedia.org/wiki/Hall_effect). But that won’t really have much impact unless the magnetic field is quite strong.

So the more precise answer to your question is “Yes, it does have an effect. But not much of one in the situation you describe.”

This will have no practical impact on a conductor like in yor example.

Magnetism does not attract electricity.

Stationary magnetic field causes moving charges (electrons in our case) to experience sideways force.

Magnetism will bend the path that the electrons go. This is [Hall effect](https://en.wikipedia.org/wiki/Hall_effect).

Basically a voltage difference forms between the sides of the conductor.

Here is simplified animation of it https://en.wikipedia.org/wiki/File:Hall_Sensor.webm (the gauge at the top is measuring the voltage between different parts of the conductor)

This can be used to make sensors.

There *is* a slight effect. A magnetic field wants to pull moving electrons onto a circular trajectory, but in a wire, they cannot really move anywhere except straight ahead. So there might be a slight increase in resistance from all the electrons being pulled to one side of the wire. However, for any magnetic field you could realistically create, the effect is going to be so small you will probably be unable to measure it.

The only meaningful interaction, as others have noted, is electromagnetic induction, which only happens if the electric current or the magnetic field are *changing* quickly. This may cause magnetism to have a significant influence, for example in transformers or motors or in the skin effect, which limits the frequency range a cable can conduct.

But no magnet will suck up your electrons.

One of major breakthroughs in science was the discovery that changing magnetic fields induce electric currents. The specific example you mentioned, though, would not be a substantial effect.