Chapter: Magnetic Effects of
Electric Current
🔹 1. Magnetic Field
Definition: Region around a magnet or a moving charge where
magnetic force acts.
Representation: By magnetic field lines.
Properties of magnetic field lines:
1. Go from North to South outside the magnet.
2. Never intersect each other.
3. Closer lines = stronger field.
4. Continuous closed loops (inside magnet, they go South to
North).
🔹 2. Magnetic Field Due to a Current-Carrying Conductor
(a) Straight Conductor
Magnetic field forms concentric circles around the wire.
Right-Hand Thumb Rule:
o Hold the wire in right hand with thumb along current; fingers
show direction of magnetic field lines.
(b) Circular Loop
Magnetic field lines form concentric circles around the loop.
At the center, the field lines are straight and perpendicular to
the plane of the loop.
Field strength ∝ Current × Number of turns / Radius.
(c) Solenoid
Solenoid = long coil with many circular turns.
Acts like a bar magnet when current passes.
One end behaves as North pole, other as South pole.
Magnetic field inside solenoid is strong and uniform.
Electric Current
🔹 1. Magnetic Field
Definition: Region around a magnet or a moving charge where
magnetic force acts.
Representation: By magnetic field lines.
Properties of magnetic field lines:
1. Go from North to South outside the magnet.
2. Never intersect each other.
3. Closer lines = stronger field.
4. Continuous closed loops (inside magnet, they go South to
North).
🔹 2. Magnetic Field Due to a Current-Carrying Conductor
(a) Straight Conductor
Magnetic field forms concentric circles around the wire.
Right-Hand Thumb Rule:
o Hold the wire in right hand with thumb along current; fingers
show direction of magnetic field lines.
(b) Circular Loop
Magnetic field lines form concentric circles around the loop.
At the center, the field lines are straight and perpendicular to
the plane of the loop.
Field strength ∝ Current × Number of turns / Radius.
(c) Solenoid
Solenoid = long coil with many circular turns.
Acts like a bar magnet when current passes.
One end behaves as North pole, other as South pole.
Magnetic field inside solenoid is strong and uniform.
