Page 119 - Physics 10_Float

ELECTROMAGNETISM

Electromagnetism is the study of magnetic effects of Interesting information
Electric charges can be
current. The use of electromagnetism in different fields of
separated into a single type. For
science and technology is very wide. Motors and electric example, you can have a single
meters are based on the effect of magnetism produced by negative charge or a single
the electric current in wires. Generators produce electric positive charge. Magnetic poles
current due to the movement of wires near very large cannot be separated. It is not
possible to have a magnetic
magnets.
north pole without a magnetic
south pole. This is a fundamental
15.1 MAGNETIC EFFECTS OF A STEADY CURRENT difference between magnetism
and electricity.
Ampere discovered that when a current passes through a For your information
conductor, it produces magnetic field around it. To Weak ionic current in our body
demonstrate this, we take a straight conductor wire and pass that travels along the nerve can
it vertically through a cardboard (Fig.15.1-a) . Now connect produce the magnetic effect.
This forms the basis of obtaining
the two ends of the conductor wire with the terminals of the images of different parts of body.
battery so that current flows through the circuit in the This is done using the technique
clockwise direction. The lines of force of the magnetic field called Magnetic Resonance
produced around the wire would be in the form of concentric Imaging (MRI). Heart and brain
are two main organs where
circles. If we place a compass needle at different points in the
significant magnetic fields can
region of magnetic field, it will align along the direction of be produced. Using MRI doctors
magnetic field. Also if we sprinkle some iron filings on the can diagnose the disorders of
cardboard around the wire, they will align themselves in brain and heart etc.
concentric circles in the clockwise direction.
Current-carrying
Current-carrying conductor
conductor
Current I Lines of
I Lines of Magnetic
Magnetic
Field
Field
Compass
Needle -
+ V
V +
-

K Paper K

(a) (b)
Current
I I
Electromagnetic Field Electromagnetic Field
(Clockwise) (Anticlockwise)
Fig. 15.1

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