Electrodynamics summary
Electrodynamics
The Right Hand Rule:
1. Use your right hand
2. Put your thumb in the direction of the current.
3. Your curled fingers then show you the direction of the magnetic field.
The magnetic field around a straight wire:
• The direction of the magnetic field can be determined by using the right hand rule.
• The magnetic field lines produced by a current in a wire form concentric circles with
the wire in the centre.
1|Page
,Electrodynamics summary
Magnetic field in a wire loop:
• On the left the current is flowing out of the page by using the right hand rule the direction
of the magnetic field can be seen.
• On the right the current is flowing out of the page by using the right hand rule the
direction of the magnetic field can be seen.
• When the arrows are in the same direction the magnetic field lines are stronger and show
that the current is flowing from left to right.
Electromagnet
• If a solid piece of iron is placed inside a solenoid we call it an electromagnet.
• Electromagnet uses: electric bells, relays and loud speakers.
• Iron is easily magnetised and loses magnetism easily too. ( a soft magnetic material)
• Steel is not used because it takes long to magnetise and retains its magnetism far
longer. ( a hard magnetic material and is better as a permanent magnet)
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, Electrodynamics summary
Magnetic field in a solenoid:
• The magnetic field around a solenoid is similar to that around a bar magnet.
• Outside the solenoid the direction of the magnetic field lines is north to south.
The direction of the north and south poles can be determined by using the
Right hand solenoid rule:
1. Use your right hand.
2. Grip the solenoid in such a way that your curled fingers point in the direction of the
current.
3. Your thumb will point towards the North Pole.
3|Page
Electrodynamics
The Right Hand Rule:
1. Use your right hand
2. Put your thumb in the direction of the current.
3. Your curled fingers then show you the direction of the magnetic field.
The magnetic field around a straight wire:
• The direction of the magnetic field can be determined by using the right hand rule.
• The magnetic field lines produced by a current in a wire form concentric circles with
the wire in the centre.
1|Page
,Electrodynamics summary
Magnetic field in a wire loop:
• On the left the current is flowing out of the page by using the right hand rule the direction
of the magnetic field can be seen.
• On the right the current is flowing out of the page by using the right hand rule the
direction of the magnetic field can be seen.
• When the arrows are in the same direction the magnetic field lines are stronger and show
that the current is flowing from left to right.
Electromagnet
• If a solid piece of iron is placed inside a solenoid we call it an electromagnet.
• Electromagnet uses: electric bells, relays and loud speakers.
• Iron is easily magnetised and loses magnetism easily too. ( a soft magnetic material)
• Steel is not used because it takes long to magnetise and retains its magnetism far
longer. ( a hard magnetic material and is better as a permanent magnet)
2|Page
, Electrodynamics summary
Magnetic field in a solenoid:
• The magnetic field around a solenoid is similar to that around a bar magnet.
• Outside the solenoid the direction of the magnetic field lines is north to south.
The direction of the north and south poles can be determined by using the
Right hand solenoid rule:
1. Use your right hand.
2. Grip the solenoid in such a way that your curled fingers point in the direction of the
current.
3. Your thumb will point towards the North Pole.
3|Page
