An electromagnet is a type of magnet that generates a magnetic field by using an electric current. Electromagnets are typically made of wire twisted into a coil. A current flowing through the wire generates a magnetic field that is focused in the hole, marking the coil’s centre.
In other words, Electromagnets are magnets produced by electric fields. They have the benefit of being able to be turned on and off, which is not the case with normal magnets. An electric motor is a basic device that makes use of electromagnets. When electricity runs through the motor, the electromagnet rotates, which causes a shaft to revolve. The rotating shaft moves other parts of the device.
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Working Principle of Electromagnet
Electromagnets consist of coils, usually, copper wrapped tightly around a laminated core of ferromagnetic material (soft iron, steel, cobalt). All electromagnets operate on the basis that an electric current in a wire (twisted on a coil) generates a magnetic field. When current flows, a magnetic field is formed, and the iron gets magnetized.
Moving charges generate magnetic fields, thus when an electric current flows through the coils of wire in an electromagnet, the coils behave like magnets. When the current is turned off, the coils cease to function as magnets.
Important Points
| Information | Description |
|---|---|
| Definition | Electromagnets use electric current to generate a magnetic field around a wire coil. |
| Working Principle | The strength of the magnetic field is directly proportional to the amount of electric current flowing through the coil. The magnetic field is created by the alignment of the atoms in the wire. |
| Daily Life Examples | Electric motors, speakers, maglev trains, and electric locks are some of the common examples of electromagnets used in everyday life. |
| Advantages | Electromagnets can be turned on and off by controlling the electric current, which makes them highly versatile and useful in a variety of applications. They can also be made to be very strong, even stronger than permanent magnets. |
| Applications | Electromagnets are used in many different industries, including manufacturing, transportation, and medicine. They are used in electric motors, generators, transformers, MRI machines, and maglev trains, among other things. |
| History | Electromagnets were first discovered in the early 19th century by Hans Christian Oersted. Later, Michael Faraday and Joseph Henry made important contributions to the development of electromagnetism. Today, electromagnetism is a fundamental concept in physics and has led to many technological advancements. |
Daily Life Examples of Devices Use Electromagnets
- An electromagnet is at the core of a doorbell. Electromagnets are made up of wire coils that are wrapped around a tiny piece of magnetic metal. When electricity flows through a wire, it generates a magnetic field surrounding it.
- Electric motors are used in electric fans, blowers, and other cooling systems. These motors operate on the electromagnetic induction principle, which is a branch of electromagnetism. According to the Lorenz force principle, the electric motor in any electrical device is moved by the magnetic field created by the electric current. The size, rating, and cost of these motors vary depending on the application.
- Locking systems for doors, which are often magnetic locking systems, are used in security systems. These systems are accessed by swiping a magnetic card or entering a security code.
- MRI machines: Medical MRI (magnetic resonance imaging) machines use powerful electromagnets to create detailed images of internal body structures.
- Speakers: Speakers use electromagnets to convert electrical signals into sound. When an electrical current is passed through a coil of wire, it creates a magnetic field that interacts with a permanent magnet, causing the speaker to vibrate and produce sound waves.
- Electric motors: Electric motors use electromagnets to convert electrical energy into mechanical energy. When an electric current is passed through a coil of wire in the presence of a magnetic field, it creates a force that can turn a rotor and produce rotational motion.
- Maglev trains: Maglev (magnetic levitation) trains use powerful electromagnets to levitate and propel the train. The train is suspended above the track by strong magnetic fields, and the magnetic force is used to push the train forward.
- Electric locks: Many modern doors and locks use electromagnets to hold the door closed until the lock is opened. When an electrical current is applied, the electromagnet attracts a metal plate that is attached to the door, holding it securely in place.
Summary
- An electromagnet is a type of magnet that uses electricity to create a magnetic field.
- The strength of an electromagnet can be increased or decreased by adjusting the amount of electrical current flowing through it.
- Electromagnets are used in many different applications, including electric motors, generators, MRI machines, and maglev trains.
- Electromagnets can be made to be very strong, even stronger than permanent magnets.
- Electromagnets are important for modern technology and have revolutionized the way we live and work.
Frequently Asked Questions
- What is an electromagnet?
A. A type of permanent magnet
B. A type of magnet that uses electricity to create a magnetic field
C. A type of magnet that can be turned off and on
D. Both B and C
Answer: D
- What is the working principle of an electromagnet?
A. The strength of the magnetic field is inversely proportional to the amount of electric current flowing through coil
B. The magnetic field is created by the alignment of the atoms in wire
C. The strength of the magnetic field is directly proportional to the amount of electric current flowing through coil
D. The magnetic field is created by the movement of the wire
Answer: C
- What are some common examples of electromagnets used in everyday life?
A. Permanent magnets
B. Refrigerator magnets
C. Electric motors, speakers, and maglev trains
D. Compasses
Answer: C
- What are some advantages of electromagnets?
A. They can be turned on and off by controlling the electric current
B. They can be made to be very strong, even stronger than permanent magnets
C. They are highly versatile and useful in a variety of applications
D. All of the above
Answer: D
- What was the role of electromagnets in the development of technology?
A. They had no role in the development of technology
B. They revolutionized the way we live and work
C. They were only used in the manufacturing industry
D. None of the above
Answer: B
Solved Problem
Problem: An electromagnet has a wire coil of 500 turns and a current of 2 amps flowing through it. What is the strength of the magnetic field produced by the electromagnet?
Solution:
We can use the formula for calculating the magnetic field produced by an electromagnet:
B = (μ * N * I) / L
where B is the magnetic field in teslas (T), μ is the permeability of free space (4π x 10^-7 Tm/A), N is the number of turns in the wire coil, I is the current in amps (A), and L is the length of the wire coil in meters (m).
In this problem, we know that N = 500, I = 2 amps, and L is not given. However, we can assume that the wire coil is tightly wound and the length is negligible compared to the diameter. Therefore, we can estimate the length of the wire coil to be approximately equal to the diameter. Let’s assume the diameter of the wire coil is 10 cm (0.1 m).
Substituting the values into the formula, we get:
B = (4π x 10^-7 Tm/A) * 500 * 2 / 0.1
B = 1.2566 x 10^-2 T
Therefore, the strength of the magnetic field produced by the electromagnet is approximately 0.0126 T.