ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: taiga on November 08, 2010, 09:25:19 pm
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I thought I had an idea of what they were until a question from TSSM 2010 threw me off (mind you i havent touched physics since august)
Does anyone have some good definitions for them, their applications, and what would happen without them? I'm having struggling understanding them :(
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>.< I just have a pre-memorized definition in my head (pre-memorized from answering the asme question so many times X.x, not rote learning it)
Commutator in a motor:
Commutator reverses direction of current through the coil every half-turn (whenever coil reaches position perpendicular to the magnetic field). Commutator achievse this by alternating contacts between ocil ends and external power supply terminals; thsi results in reversal of magnetic forces acting on the coil, thereby maintaining a torque (and thus rotation) of consistent direction. Without commutator, coil will oscillate about position perpendicular to the magnetic field until it comes to a halt at that position.
Commutator in a generator
Commutator reverses polarity of the output current every half turn (whenever coil reach position perpendicular to the magnetic field), thereby producing a variable DC output current (as coil current switches direction every half turn as well.
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Ims ory what is an OCIl end?
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Split rings = for DC current (reverses the current every half turn, to change the dir. of forces so that the motor keeps spinning is a constant direction)
The graph for this is like a (sin(x))^2 graph. You never get voltage or current below the x axis
Slip rings = AC current. These works with alternators (where a magnet rotates inside a stationary coil) and generators (coil rotates about a stationary magnet). The graph for voltage and current is a simple sin curve. . .
BTW - Commutators and Split rings are only used for DC voltage
hope that helps :)
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>.< I just have a pre-memorized definition in my head (pre-memorized from answering the asme question so many times X.x, not rote learning it)
Commutator in a motor:
Commutator reverses direction of current through the coil every half-turn (whenever coil reaches position perpendicular to the magnetic field). Commutator achievse this by alternating contacts between ocil ends and external power supply terminals; thsi results in reversal of magnetic forces acting on the coil, thereby maintaining a torque (and thus rotation) of consistent direction. Without commutator, coil will oscillate about position perpendicular to the magnetic field until it comes to a halt at that position.
Commutator in a generator
Commutator reverses polarity of the output current every half turn (whenever coil reach position perpendicular to the magnetic field), thereby producing a variable DC output current (as coil current switches direction every half turn as well.
hahaha. This happened to me too. It's the same question on every third party exam :)
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Ims ory what is an OCIl end?
coil end haha
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LOl phew ohkay :P
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Okay so when a question asks me if a Commutator or a slip ring is ideal for a DC supply motor, I immediately call it as a commutator as Slip-Rings are only AC.
But what if it were to ask if a Split ring or a Commutator would be ideal, what would I be looking to say then?
or a Commutator = split ring commutator?
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Okay so when a question asks me if a Commutator or a slip ring is ideal for a DC supply motor, I immediately call it as a commutator as Slip-Rings are only AC.
But what if it were to ask if a Split ring or a Commutator would be ideal, what would I be looking to say then?
split-ring commutator =D