Electromagnet

Electromagnets are temporary magnets that form a magnetic field when an electric current is passed through them. These magnets are made by coiling a wire around an iron core. When electric current is passed through it, the iron core behaves like a magnet but when the current is turned off, it loses all its magnetic properties. Electromagnets are widely used in various devices like motors, electric bells, solenoids, etc. 

In this article, we will understand the meaning of electromagnet, properties of electromagnet, advantages and disadvantages, the right-hand rule of electromagnetic field, uses of electromagnet, and the difference between permanent magnets and electromagnet.

What is Electromagnet?

Electromagnet is a magnet that forms a magnetic field around it when electricity is passed through it. When the electricity stops, the magnetism also stops working. These magnets are termed as temporary magnets. The strength of its magnetic field depends upon various factors like:

• number of times the wire is wound.
• the electricity flowing through it, and
• the material of the core.

Electromagnets are commonly used when a magnetic field needs to be turned on or off. They are mainly found in motors, MRI machines, generators, solenoids, etc.

Electromagnet Definition

An electromagnet is a magnet powered by electricity, creating a magnetic field that can be controlled. It works by passing an electric current through a coil of wire.

Examples of Electromagnet

Electromagnets are widely used in various industries. Some examples where electromagnets are used are:

Electric Doorbell

Many doorbells use an electromagnet to produce sound. When the doorbell button is pressed, an electric current flows through a coiled wire, creating a magnetic field that attracts a metal rod. The rod strikes a bell, generating a ringing sound. Once the button is released, the circuit is broken, and the magnetic field disappears, allowing the bell’s spring to return the rod to its original position.

Card Reader

The magnetic strip on credit cards and ID cards contains tiny particles oriented in a specific pattern. When the card is swiped through a card reader, an electromagnet in the reader creates a magnetic field. This field induces changes in the magnetic orientation of the particles on the card’s strip .Sensors in the reader detect these changes and convert them into electrical signals. The system interprets these signals as data, enabling card transactions.

MRI Machine

Magnetic Resonance Imaging (MRI) machines in healthcare use superconducting electromagnets. These magnets, when cooled to extremely low temperatures, become superconductors with zero electrical resistance. This allows a detailed imaging of internal body structures thus creating high-resolution medical images.

Electric Generators

Electromagnets play a crucial role in electric generators. As a coil of wire rotates within a magnetic field, an electric current is induced in the wire due to electromagnetic induction. This generated current is then harnessed as electrical energy. The strength and control of the magnetic field in the generator are essential for efficient electricity production.

Electromagnetism Formula

The formula for the magnetic field (B) produced by an electromagnet is given by Ampere’s Law.

Ampere’s Circuital Law : It states that the line integral of a magnetic field around a closed loop is equal to μ_° times the algebraic sum of the current passing through it.

Thus, the Electromagnetic Formula is given as follows:

​

where:

• B is the magnetic field strength in tesla (T),
• μ is the permeability of the material (measured in henrys per meter, (H/m),
• I is the current flowing through the coil in amperes (A),
• N is the number of turns in the coil, and
• L is the length of the coil in meters (m).

Working Principle of Electromagnet

The working principle of electromagnets depends on the relationship between electric currents and magnetic fields. When an electric current flows through a conductor, for example, a wire, it produces a magnetic field around it. By coiling the wire, the resulting magnetic field is strengthened. This coil, when connected to a power source, becomes an electromagnet.

• The strength of the magnetic field can be controlled by adjusting the electric current.
• This property makes electromagnets versatile and widely used in various applications, from everyday devices like doorbells to more complex systems such as magnetic resonance imaging (MRI) machines in healthcare.

Types of Electromagnet

The electromagnets are mainly classified as

• Resistant Electromagnets
• Superconducting Electromagnets
• Hybrid Electromagnets
• Solenoid Electromagnets
• Toroidal Electromagnets

Resistant Electromagnets 

These electromagnet uses copper wires to create a magnetic field around them. The magnetic field is created when the copper wire is twisted around a piece of iron and an electric current is induced in the wire. The number of twits of the copper wires is directly proportional to the strength of magnetic field.

Superconducting Electromagnets

Superconducting electromagnets are crafted from materials displaying zero electrical resistance to the current flowing through them under low temperature. This property allows for the creation of magnetic fields even after power supply is cut off. These types of electromagnets are applied in certain scientific instruments like Magnetic Resonance Imaging (MRI) machines and particle accelerators due to their capability to generate powerful and stable magnetic fields.

Hybrid Electromagnets

Hybrid Electromagnets are a mixture of the two types of electromagnets i.e. resistive and superconductor electromagnets. They are commonly used in Spaceships, frictionless bearings, etc.

Solenoid Electromagnets

Solenoid electromagnets feature a coiled wire wound in a helical shape. When an electric current passes through this coil, it produces a strong and uniform magnetic field. These solenoids serve versatile roles in devices, functioning as switches, actuators, or integral components in locking mechanisms.

Read More, Solenoid Magnetic Field

Toroidal Electromagnets

Toroidal electromagnets take on a torus or ring shape with wire coiled around. This design improves the magnetic field, making it particularly effective within the core of the toroid. These are widely used in telecommunications and modern medical equipments, toroidal electromagnets excel in efficiently confining and directing magnetic fields.

Read More, Solenoid and Toroid Magnetic Field

How to Make a Simple Electromagnet?

Creating a basic electromagnet involves a simple process using readily available materials.

Simple Electromagnet

Materials Required

• A nail or a piece of iron
• Insulated copper wire
• A battery (AA or AAA batteries are suitable)
• Electrical tape

Steps to Make Electromagnets

• Prepare the Wire: Take a piece of insulated copper wire, approximately 1 to 1.5 feet in length, and strip about an inch of insulation from both ends of the wire, exposing the bare copper.

• Wrap the Wire Around the Nail: Wrap the wire tightly and evenly around the nail or iron piece. Ensure a neat winding along the entire length of the nail, leaving a few inches of unwound wire at both ends.

• Secure the Wire: Use electrical tape to firmly secure the wound wire in place, preventing any loose ends.

• Connect the Wire to the Battery: Attach one end of the wire to one terminal of the battery and the other end to the opposite terminal.

• Test the Electromagnet: Once the wire is connected to the battery, the nail or iron piece becomes magnetized. Test its magnetism by attracting small metal objects like paper clips.

• Experiment and Explore: Check the impact of variations, such as increasing the number of wire turns or using a stronger battery, to observe how they influence the electromagnet’s strength.

Right-Hand Rule of Electromagnetic Field

The right-hand rule for the electromagnetic field is a guideline used to determine the direction of magnetic field around the wire. Point the thumb of right hand in the direction of the flow of electric current in a wire and then curl your fingers. This curl of the fingers indicates the direction of electric field.

Right-hand Rule

Uses of Electromagnet

The uses of Electromagnet are given below:

• Electromagnets are used in electric motors to generate motion.

• Electromagnets are used in solenoids for tasks like actuating switches and valves.

• Magnetic lift systems use electromagnets to lift and move heavy metal objects.

• MRI machines in medical settings use strong electromagnets for imaging.

• Scrap yards use large electromagnets to lift and transport metal scrap.

• Speakers and headphones employ electromagnets to produce sound waves.

Characteristics of Electromagnets

Characteristics of electromagnets are as follows:

• Control Magnetic Field: Electromagnets can adjust their magnetic field strength by controlling the electric current, ensuring a precise magnetic field.

• Temporary Magnetism: It exhibits magnetic characteristics only when an electric current is present, enabling flexible activation and deactivation for specific applications.

• Versatility in Design: Comes in varied shapes and sizes, such as flat-faced, cylindrical, and specialized configurations, adapting to diverse industrial and technological needs.

• Industrial Use: Widely employed in industry for tasks like material handling, sorting, and efficient lifting of ferrous materials due to robust magnetic fields.

• Safety: The temporary magnetic field enhances safety, allowing easy control and manipulation of magnetic force in different settings.

• Energy Efficienct: Consumes power only during active magnetic field generation, contributing to economical energy usage.

• Technological Applications: Vital in various technologies, including electric generators, MRI machines, and electric door locks, showcasing versatility in different technological domains.

Disadvantages of Electromagnet

Electromagnets being versatile and efficient still have few drawbacks. The Disadvantages of the Electromagnets are listed below:

• Power Dependency: Electromagnets rely on a continuous supply of electric power to maintain their magnetic field. Once the power is cut off, the magnetism disappears.

• Heat Generation: The flow of electric current through the coils can generate heat, and in some cases, this heat needs to be managed to prevent damage to the electromagnet.

• Complexity: Building and maintaining electromagnets can be more complex than working with permanent magnets, especially in systems requiring intricate control of magnetic fields.

• Cost: The equipment and technology needed for creating and controlling electromagnets can be more expensive than those associated with permanent magnets.

• Size and Weight: In certain applications, the size and weight of electromagnets may pose challenges, especially if space and weight are critical factors.

Difference Between Electromagnet and Permanent Magnet

The key difference between Electromagnet and a Permanent Magnet is as follows:

Electromagnet VS Permenant Magnet
Aspect	Electromagnet	Permanent Magnet
Magnetism	Formed by passing an electric current through a coil of wire.	Inherently magnetic, without the need for an external force
Adjustability	Magnetic strength can be controlled by regulating the current.	Fixed magnetic strength based on material composition.
Temporary/Permanent	Magnetism is temporary and stops when the current is switched off.	Magnetism is permanent unless subjected to demagnetization.
Materials Used	Requires a coil of wire and a core material.	Made of materials with natural magnetic properties.
Applications	Used in devices requiring adjustable magnetic fields, such as motors, generators, and solenoids.	Commonly found in everyday items like refrigerator magnets, compass needles, and magnetic toys.
Power Dependency	It depends on electric power to generate a magnetic field.	It does not require any external power to maintain magnetism.

Read More,

• Magnet
• Permanant and Electromagnets
• Magnetic Field

Electromagnets: FAQs

What is an Electromagnet?

An electromagnet is a type of magnet created by passing an electric current through a coil of wire. It generates a magnetic field that can be controlled and turned on or off.

What is a Magnet?

A magnet is an object or material that produces a magnetic field. It can attract certain materials like iron, nickel, and cobalt. Magnets have two poles, north and south, and exhibit the properties of attraction and repulsion.

Is an Electromagnet a Temporary Magnet?

Yes, an electromagnet is a temporary magnet. It only exhibits magnetic properties when an electric current is flowing through its coils. The magnetism disappears when the current is switched off.

What is the Principle on which Electromagnets Work?

The principle underlying the operation of electromagnets is the interaction between electric current and magnetic fields. When an electric current flows through a conductor, it generates a magnetic field, creating an electromagnet.

How Electromagnet Works?

Electromagnets function by utilizing the magnetic field produced when an electric current passes through a coil of wire. The coil enhances the magnetic strength, and this magnetic force can be controlled by adjusting the current.

Are Electromagnet and Solenoids the Same?

An electromagnet is a magnet whose magnetic properties depends upon the electric current. A solenoid, on the other hand, behaves like an electromagnet, when an electric current passes through it. Therefore, every solenoid can be an electromagnet but every electromagnet need not be a solenoid.

What are the Examples of Electromagnet?

Examples of electromagnets include those used in various everyday devices such as electric doorbells, magnetic locks, MRI machines in healthcare, and the magnetic strip on credit cards.