8th grade ch. 3 sec. 2 electricity, magnetism & motion
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TRANSCRIPT
Ch. 3 Ch. 3 Sec. 2 Electricity, Sec. 2 Electricity,
Magnetism & MotionMagnetism & Motion
energyenergy ability to move ability to move an object some an object some distancedistance
electrical electrical energyenergy
energy assoc. w/ energy assoc. w/ electric currentselectric currents
mechanical mechanical energyenergy
energy due to an energy due to an object’s movement object’s movement or positionor position
When current-carrying wire is placed in magnetic field,When current-carrying wire is placed in magnetic field,
electrical energy electrical energy mechanical energy mechanical energy
GalvanometerGalvanometer Device that measures small currentsDevice that measures small currents Converts electrical energy Converts electrical energy
mechanical energymechanical energy HOW IT WORKS:HOW IT WORKS:
Current passes thru loops of wire in Current passes thru loops of wire in magnetic fieldmagnetic field
Magnetic field from wire interacts Magnetic field from wire interacts with magnet’s fieldwith magnet’s field
Causes loops of wire & pointer Causes loops of wire & pointer attached to loops to rotate ½ turnattached to loops to rotate ½ turn
Current does not reverseCurrent does not reverse
GalvanometerGalvanometer
Electric MotorElectric Motor Device that uses electric current to Device that uses electric current to
turn axleturn axle Converts electrical energy Converts electrical energy
mechanical energymechanical energy Loop of current-carrying wire Loop of current-carrying wire
(armature) spins continuously(armature) spins continuously
Electric Electric MotorMotor
Parts of a MotorParts of a Motor
device that device that reverses flow reverses flow of current of current
Brushes andcommutator
CommutaCommutatortor
Parts of a MotorParts of a Motor
contact points contact points that connect that connect commutator to commutator to current sourcecurrent source
BrushesBrushes
Brushes andcommutator
Parts of a MotorParts of a Motor
wires wires wrapped wrapped around around iron coreiron core
Armature
ArmatureArmature
armaturearmature
Armature
In this figure, the armature winding has been left out so that it is easier to see the commutator in action. The key thing to notice is that as the armature passes through the horizontal position, the polesof the electromagnet flip. Because of the flip, the north pole of theelectromagnet is always above the axle so it can repel the field magnet's north pole and attract the field magnet's south pole.
MOTORS EVERYWHERE !
Look around your house and you will find that it is filled with electric motors.
The fan over the stove and in the microwave oven
The blender The can opener
The refrigerator – Two or three in fact: one for the
compressor, one for the fan inside the
refrigerator, as well as one in the icemaker The mixer
Probably even the clock on the oven.
Starting in the kitchen, there are motors in:
In the garage, there is an In the garage, there is an electric motor inelectric motor in
The washer The washer The dryer The dryer The electric screwdriver The electric screwdriver The vacuum cleanerThe vacuum cleaner The electric saw The electric saw The electric drill The electric drill
The fan The fan The electric The electric
toothbrush toothbrush The hair dryer The hair dryer The electric razor The electric razor
Even in the bathroom, there’s a motor in: