Class 10th Revision Notes Magnetic Effect of Electric Current, Physics

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Magnetic effect of Electric Current

The term ‘magnetic effect of electric current’ means that ‘an electric current flowing in a wire produces a magnetic field around it’.

In other Words,

Electric current can produce magnetism.

Magnetic Field

The space surrounding a magnet in which magnetic force is exerted, is called a magnetic field.
The direction of magnetic field at a point is the direction of the resultant force acting on a hypothetical north pole placed at that point.

Magnetic Field Lines

The magnetic field lines drawn in a magnetic field along which a north magnetic pole would move.

The magnetic field lines are also known as magnetic lines of force.

The magnetic field lines always begin from the N-pole of a magnet and end on the S-pole of the magnet.

Properties of the Magnetic Field Lines

• The magnetic field lines originate from the north pole of the magnet and end at its south pole.
• The magnetic field lines come closer to one another near the poles of a magnet but they are widely separated at other places.
• The magnetic field lines do not intersect (or cross) one another.

Magnetic Field of Earth

• The axis of earth’s magnet and geographical axis do not coincide with each other.
• The axis of earth’s magnetic field is inclined at an angle of about 15 degree with the geographical axis.
• The earth magnetism is due to the magnetic effect of current (which is flowing in the liquid core at the centre of the earth). Thus, Earth is huge electromagnet.

Magnetic Effect of Current or Electromagnetism

It was concluded that a current flowing in a wire gives rise to a magnetic field around it.

Magnetic Field Pattern due to a Circular loop

The magnitude of a magnetic field produced by a current-carrying circular loop (or circular wire) at its centre is:
• Directly proportional to the current passing through the circular loop (or circular wire), and
• inversely proportional to the radius of circular loop (or circular wire).

Clock Face Rule

According to clock face rule, look at one face of circular wire (or coil) through which a current is passing:
• If the current around the face of circular wire (or coil) flows in a Clockwise direction, then that face of a circular wire will be South pole (S-pole).
• If the current around the face of circular wire flow in the Anticlockwise direction,  then that face of circular wire will be a North pole (N-pole).

Note: If the direction of current in the front face of circular wire is clockwise, then the direction of current in the back face of the circular wire will be anticlockwise

Magnetic Field Due to Solenoid

The solenoid is long coil containing a large number of close turns of insulated copper wire.
The magnetic field produced by current-carrying solenoid is similar to the magnetic field produced by a bar magnet.
– The Strength of magnetic field produced by a current carrying solenoid depends on:
• The number of turns in the solenoid. Larger the number of turns in the solenoid, greater will be the magnetism produced.
• The strength of current in the solenoid . Larger the current passed through solenoid, stronger will be the magnetic field produced.
• The nature of “core material” used in making solenoid. The use of soft iron rod as core in a solenoid produces the strongest magnetism.

Electromagnet

An electric current can be used for making temporary magnets known as electromagnets.
An electromagnets works on the magnetic effect of current.

An electromagnet is a magnet consisting of a long coil of insulated copper wire wrapped around a soft iron core that is magnetised only when electric current is passed through the coil.

The core of an electromagnetic must be of soft iron because soft loses all of its magnetism when current in the coil is switched off.

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