Copper in its purest form is non-magnetic. It however demonstrates weak magnetic properties when subjected to strong external magnetic fields. Copper repulses magnets but at a weaker level compared to magnetic metals.
Basic Magnetic Properties of Copper
Copper is renowned and extensively used in electrical wiring due to its impressive conductivity. It is also renowned for its non-magnetic properties. Here are its primary properties and how they influence its magnetism.
· Atomic Structure
A copper atom typically consists of 29 electrons, which are distributed in shells that surround its nucleus. Most of these electrons are arranged in pairs and this leads to their spins nullifying each other. This consequently reduces the likelihood of copper becoming magnetized and makes copper weakly repulsive to magnets.
· Thermal Properties
Copper is universally renowned for its superior thermal conduction. The eddy currents produced when copper is exposed to a strong magnetic field lead to heat generation. This stable thermal property ensures that copper retains its diamagnetic nature even when exposed to power external magnetic forces.
· Conductivity
Copper is characterized by a strong electrical conductivity and this explains why it is extensively used in electrical wiring. Its electrons are free to move and this elevates its conductivity. This free electron movement, however, does not impact their magnetism. The electrons do not align with external magnetic fields leading to non-magnetism.
· Magnetic Susceptibility
When you subject a copper object to a strong magnetic field, it hardly becomes magnetized due to its negative magnetic susceptibility. This means that its electrons do not align with external magnetic field lines under normal conditions. Its low magnetic susceptibility contributes to its poor magnetic properties.
How to Magnetize Copper
Although copper is naturally non-magnetic, you can turn a copper object into a magnet using varying methods.
· Electromagnetic Induction
Electromagnetic induction is primarily used to induce temporary magnetism in copper. To achieve this, you will need to induce a powerful magnetic field using electricity. You will need a coil of wire, which you can bundle around your copper object, and a power source.
Once you switch on the power source, the current flowing through the wire will forcefully align the object’s atoms to the magnetic field lines. This will lead to temporary magnetism, which fades away once you switch off the power source.
· Alloying
Alloying involves blending pure copper with traces of magnetic elements like nickel and manganese. Exposing the resulting compound to strong magnetic fields can induce permanent magnetism due to the strong magnetic properties of the respective alloys.
· High-Pressure Induction
You can also induce magnetic capabilities in copper by subjecting it to high pressure, typically several gigapascals. The high pressure changes the copper’s crystalline configuration resulting in an electron arrangement that favors magnetism.
Factors Affecting Copper’s Magnetism
The response or reaction copper demonstrates when exposed to magnetic forces differs under different conditions. Here are some of the factors that greatly impact copper’s magnetic behavior.
· External Magnetic Field
Copper is considered diamagnetic due to the relatively poor repulsion it exhibits when subjected to external magnetic fields. This is a result of the copper’s magnetic moments combating alignment with external magnetic field lines.
· Temperature
In extremely high temperatures, copper tends to exhibit lower magnetic repulsion due to misaligned magnetic moments. Lowering temperature, on the contrary, induces superconductivity which leads to stronger repulsion in the face of magnets.
· The Presence of Alloys
Injecting ferromagnetic elements like iron and nickel into pure copper enhances its magnetic properties. The copper assumes the magnetic capabilities of the alloys resulting in magnetism. The resulting material can be used to undertake varying magnetic applications like magnetic separation.
· Impurities
Copper devoid of impurities is characteristically diamagnetic but once impurities are introduced, its magnetic behavior changes. The presence of ferromagnetic impurities tends to induce stronger magnetic properties in copper whereas the presence of non-magnetic impurities weakens its properties.
· Electric Current
Electric current induces temporary magnetism in copper. Once you wrap an object made of pure copper with a wire carrying electricity, the object is likely to become magnetized. However, removing the wire or disconnecting it from power leads to the loss of magnetism.
· Shear Strain
Force can significantly change the structure and electron arrangement of your copper object. This can result in altered magnetic properties. For instance, hitting a copper object with a hammer will influence its response to magnetic fields.
Demonstration of Copper’s Non-Magnetic Nature
To determine copper’s reaction to magnets, you will primarily need a copper object and a strong magnet. You might also need a piece of paper and a flat surface.
- First, wipe your magnet with a piece of tissue to dislodge dust and other impurities that may impact its magnetic properties.
- Then place your magnet on a flat surface such as a table.
- Bring your copper object towards the magnet slowly and carefully. Do not let the two come into contact.
Observation
As you bring the copper rod closer to the magnet, you will notice that it does not get drawn to the magnet. On the contrary, you might notice a slight repulsion, which explains copper’s diamagnetic properties.
Magnetic Uses of Copper
Under certain conditions, pure copper demonstrates diamagnetic characteristics, which result in weak revulsion. As such, copper is often used in applications necessitating its diamagnetic properties.
- Magnetic Shielding: If you have certain equipment that needs to be protected from external magnetic forces, you can use copper to shield it. This is because it repulses magnetic fields.
- Magnetic Coating: Copper is also often applied to magnetic objects to improve their functionality. For instance, it is used on magnetic storage devices like tapes to elevate their functionality.
- Making of Electromagnets: The wire used to wrap the ferromagnetic material in electromagnets is predominantly made from copper. This is because it is highly conductive.
- Transformer Coils: The primary and secondary coils used to transmit energy in transformers are typically made of copper.
- Magnetic Levitation: Due to its diamagnetic nature, copper is often used to manufacture objects that need to be suspended in air via magnetic levitation.
More Resources:
Copper Melting Point – Source: HM
Magnetic Properties of Copper – Source: UMD
List of Magnetic Metals – Source: SCIENCING