Transcript Electromagnetism - Sterling Public Schools

Electromagnetism
It’s attractive!
(or repulsive)
Electromagnetism rules
• Magnetic fields exist in the
region near a conductor when
the circuit is closed.
• The direction of the field is
dependent on the direction of
the current in the conductor.
The intensity or strength of an electric
or magnetic field can be determined by
the lines representing it. The field
intensity is proportional to the number
of lines of force per unit area normal to
the field. High intensity is represented
by lines drawn close together, low
intensity is represented by lines more
widely separated.
Ampere’s Rule for a Straight
Conductor:
Grasp the conductor in the
right hand with the thumb extended
in the direction of the positive
current. The fingers then will circle
the conductor in the direction of the
magnetic flux.
Ampere’s Rule for a Solenoid:
Grasp the coil in the right
hand with the fingers circling the
coil in the direction of the positive
current. The extended thumb will
point in the direction of the North
pole of the core.
Electromagnetic
Induction
• An electric generator converts
mechanical energy to electrical
energy.
• An electric motor converts
electrical energy to mechanical
energy.
Generator Rule
Right Hand
Extend thumb, forefinger, and the middle finger of the
right hand at right angles to each other. Let the
forefinger point in the direction of the B flux from
North to South and the thumb in the direction the
conductor is moving. The middle finger points in the
direction of the induced positive current.
Motor Rule
Left Hand
Extend the thumb, forefinger, and middle finger of the
left hand at right angles to each other. Let the forefinger
point in the direction of the B flux and the middle finger
in the direction of the positive current. The thumb points
in the direction of the motion of the conductor.