What is Electromagnetism
Electromagnetism is the type of magnetism produced by an electric current. This phenomenon was discovered in 1819 when a Danish scientist named Hans Oersted noticed the needle on a magnetic compass moved if it was put close to an electric wire.
Before his discovery, scientists believed that electricity and magnetism were two different scientific phenomena. Then, in 1825, an English physicist named William Sturgeon created the first use – able electromagnet that could easily lift a 9 pounds iron piece.
What is Electromagnetism?
Electromagnetism is a process where a magnetic field is created by introducing the current in the conductor. When a conductor is electrically charged it generates magnetic lines of force of conductor. For example, if current i.e., positive charges moving in a wire, it produces the magnetic field along the wire, and the direction of magnetic lines and force can be determined using Right-hand Rule. Refer to the image for a detailed explanation
difference between a permanent magnet and electromagnet?
1. Permanent magnet
The South – North polarity of a permanent magnet is fixed. It cannot be changed.
Its strength cannot be altered.
The South – North polarity of an electromagnet can be altered by changing the direction of the current in the coil.
Its strength can be altered by changing the current flowing in it or by changing the number of turns in it.
FLEMING’S RIGHT-HAND RULE
Fleming’s right-hand rule is used to determine the direction of induced current in the conductor when it moves in a region of the magnetic field. British physicist John Ambrose Fleming proposed this rule in the late 1800s. Applying the right-hand rule, stretch the thumb and the index and middle fingers so that they are perpendicular to each other. If the index finger indicates the direction of the magnetic field and the thumb shows the direction of the motion of the conductor, then the second or middle finger will show the direction of the induced current. The right-hand rule is applicable to positive charges and to the theoretical flow of current. The theoretical flow of current is similar to the conventional current which flows from positive to the negative end
The thumb pointing upwards indicates the direction of the current by convection that is opposite to the actual flow of the current. The curled fingers around the wire show the direction of the magnetic field.
FLEMING’S LEFT-HAND RULE
Fleming’s Left-Hand Rule illustrates what happens when charged particles such as electrons in a current enter a magnetic field. To demonstrate left-hand rule, hold on to an object that represents the wire. If the forefinger represents the direction of the field and the second finger represents that of the current, then thumb gives the direction of the force.
A magnetic field is produced by an electric current flowing through a conductor. A force is exerted as well by this magnetic field on the magnet that is placed in the surroundings of the conductor. French scientist Andre Marie Ampere discovered that an equal and opposite force is exerted by the magnet on the current-carrying conductor. Various experiments showed that the direction of the force exerted is reversed when the direction of the current through the wire is reversed. Thus, the direction of the force on the wire depends on the direction of the current and the magnetic field. When the direction of the current is at a right angle to the direction of the field, the magnitude of the force is at the highest. In such conditions, we can use a simple rule such as the Left-Hand Rule to find the direction of the force on the wire.
Suppose while shopping you go cashless and your parents use cards. The shopkeeper always scans or swipes the card. Shopkeeper does not take a photo of the card or tap it. Why does he swipe/scan it? And how does this swiping deduct money from the card? This happens because of the ‘Electromagnetic Induction’.
Can moving objects produce electric currents? How to determine a relationship between electricity and magnetism? Can you imagine the scenario if there were no computers, no telephones, no electric lights. The experiments of Faraday has led to the generation of generators and transformers.
The induction of an electromotive force by the motion of a conductor across a magnetic field or by a change in magnetic flux in a magnetic field is called ‘Electromagnetic Induction’.
This either happens when a conductor is set in a moving magnetic field (when utilizing AC power source) or when a conductor is always moving in a stationary magnetic field.
According to Faraday’s Law, the relative motion between magnetic field and conductor, the flux linkage changes and this change in flux induces a voltage across the coil.
Explanation with an example
DC Generator works on the principle of Faraday’s Law of Electromagnetic Induction. It is a system that converts mechanical energy into electrical energy.
In the above figure, A rectangular conductor width sides are placed in between a magnetic field. When the rectangular conductor rotates in between magnetics, it cuts the magnetic field thereby causing the Electromagnetic field (e m f).
Making a simple electromagnet
All of you know that a nail is not a magnet. However, it can be turned into one if you wrap a wire coil, called a solenoid, around it.
Material required –
3 Steps to make a simple electromagnet
Wrap the copper wire onto the nail. Make sure that the wire-coils are very close and tight.
Wrap the copper wire ends tightly to the top of the battery on both sides where the positive and negative charges are located.
Now, move the contraption on the top of the paper clips that you have. You would be able to easily lift them without touching them. This is electromagnetism at work!
6 Uses of electromagnetism
Electromagnets produce much more powerful magnetic fields than permanent magnets. The power of the electromagnets can be adjusted by changing the amount of current flowing through it. Electromagnets find their uses in many things that we use in our everyday lives.
They are used in cell phones that work on the interaction between the phone signals and magnetic pulses produced by an electromagnet inside the phone.
Electromagnets are also used in magnetic resonance imaging (MRI) machines that help us to look inside the human body.
Loudspeakers use electromagnets to produce sound.
Electromagnets make it easy to handle large chunks of scrap metal via cranes.
Modern generators also require electromagnets to function efficiently.
Applications of Electromagnetic Induction
Electromagnetic induction in AC generator
Magnetic Flow Meter
Frequently Asked Questions on Electromagnetism
What is Electromagnetism?
Electromagnetism is a branch of physics that involves the study of the electromagnetic force. It is a type of interaction that occurs between electrically charged particles.
Define electromagnetic force?
The electromagnetic force is a force that acts between charged particles and is a combination of electrical and magnetic forces.
State Faraday’s Law?
Faraday’s Law states that whenever there is relative motion between magnetic field and conductor, the flux linkage changes and this change in flux induces a voltage across the coil.
Define electromagnetic induction?
Electromagnetic induction is the production of an electromotive force across an electrical conductor in a changing magnetic field.
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