CHAPTER – 13
MAGNETIC EFFECTS OF
ELECTRIC CURRENT
In this chapter, we will study the effects of electric current :
1. Hans Christian Oersted (1777-1851)
Oersted showed that electricity and magnetism are related to each other. His
research later used in radio, television etc.
The unit of magnetic field strength is name Oersted in his honour.
2. Oersted Experiment
R K
X
XY is conductor (Cu wire)
through which current is passed
Y
– +
On passing the current through the copper wire XY in the circuit, the compass
needle which is placed near the conductor gets deflected. If we reverse the
direction of current, the compass needle deflect in reverse direction. If we
stop the flow of current, the needle comes at rest.
Hence, it conclude that electricity and magnetism are linked to each other. It
shows that whenever the current will flow through the conductor, then
magnetic field around. it will developer
3. Magnetic Field – It is the region surrounding a magnet, in which force of
magnet can be detected. It is a vector quantity, having both direction &
magnitude.
4. Compass needle– It is a small bar magnet, whose north end is pointing
towards north pole and south end is pointing towards south pole of earth.
5. Magnetic field lines–
When a bar magnet is placed on a card board and iron fillings are sprinkled,
they will arrange themselves in a pattern as shown below.
137 X-Science
, N S
The lines along which the iron filling align themselves represent magnetic
field lines.
Hence, magnetic field line is a path along which a hypothetical free north pole
tend to move towards south pole.
6. Characteristics of Magnetic field lines :
(1) The direction of magnetic field lines outside the magnet is always from
north pole to south pole of bar magnet and are indicated by an arrow.
Inside the magnetic, the direction of field lines is from its south pole to north
pole
Thus magnetic field lines are closed curve
(2) The strength of magnetic field is expressed by the closeness of magnetic
field lines. Closer the lines, more will be the strength and farther the lines, less
will be the magnetic field strength.
(3) No two field lines will intersect each other.
If they intersects, then at point of intersection the compass needle will show
two direction of magnetic field which is not possible.
Tangent at the
point of intersection
shows two direction.
7. Magnetic field due to Current Carrying Conductor
N N
x S y x S y
Cu wire Cu wire
+ – – +
(a) (b)
138 X-Science
MAGNETIC EFFECTS OF
ELECTRIC CURRENT
In this chapter, we will study the effects of electric current :
1. Hans Christian Oersted (1777-1851)
Oersted showed that electricity and magnetism are related to each other. His
research later used in radio, television etc.
The unit of magnetic field strength is name Oersted in his honour.
2. Oersted Experiment
R K
X
XY is conductor (Cu wire)
through which current is passed
Y
– +
On passing the current through the copper wire XY in the circuit, the compass
needle which is placed near the conductor gets deflected. If we reverse the
direction of current, the compass needle deflect in reverse direction. If we
stop the flow of current, the needle comes at rest.
Hence, it conclude that electricity and magnetism are linked to each other. It
shows that whenever the current will flow through the conductor, then
magnetic field around. it will developer
3. Magnetic Field – It is the region surrounding a magnet, in which force of
magnet can be detected. It is a vector quantity, having both direction &
magnitude.
4. Compass needle– It is a small bar magnet, whose north end is pointing
towards north pole and south end is pointing towards south pole of earth.
5. Magnetic field lines–
When a bar magnet is placed on a card board and iron fillings are sprinkled,
they will arrange themselves in a pattern as shown below.
137 X-Science
, N S
The lines along which the iron filling align themselves represent magnetic
field lines.
Hence, magnetic field line is a path along which a hypothetical free north pole
tend to move towards south pole.
6. Characteristics of Magnetic field lines :
(1) The direction of magnetic field lines outside the magnet is always from
north pole to south pole of bar magnet and are indicated by an arrow.
Inside the magnetic, the direction of field lines is from its south pole to north
pole
Thus magnetic field lines are closed curve
(2) The strength of magnetic field is expressed by the closeness of magnetic
field lines. Closer the lines, more will be the strength and farther the lines, less
will be the magnetic field strength.
(3) No two field lines will intersect each other.
If they intersects, then at point of intersection the compass needle will show
two direction of magnetic field which is not possible.
Tangent at the
point of intersection
shows two direction.
7. Magnetic field due to Current Carrying Conductor
N N
x S y x S y
Cu wire Cu wire
+ – – +
(a) (b)
138 X-Science
