Identify problems with experiment question... (2 Viewers)

[fush]

for 3 marks:
- coil not connected to cummutator
- brushes not connected to externa power source
- brushes were made of copper instead of carbon (graphite)

 

[ShaunSmith]

woohoo + writing cause msg isnt long enough

 

[fush]

they would still give u 3 marks as it said list (if i remember corect)

 

[ShaunSmith]

no i meant "woohoo" isnt a long enough msg to submit lol.
i only did dot points.

 

[gordo]

the coils were coiled in opposite directions on the rotor
the coils were not connected to the commutator
there was no power supply

 

[ShaunSmith]

they are supposed to be coiled in oppisite direction if the coil same direction current same direction therefore force same direction and no turning

 

[gordo]

they are supposed to be coiled in the same direction...
the polarity of the magnet is different on opposite sides, if u change the direction of the current to, u will end up with a net torque of zero

 

[ShaunSmith]

they are supposed to be coiled in the same direction...
the polarity of the magnet is different on opposite sides, if u change the direction of the current to, u will end up with a net torque of zero

polarity doesnt have anything to do with it, magnetic field goes from north to south.

 

[angelduck]

amm lets c...
*Brushes should be made of graphite/carbon not copper
*no power source
*coil not connected to split ring commutator

ditto! I soo had sometin really stupid, cant remember it know, but i then realised later that there was no external circuit!
Woo Pee@

 

[kunny funt]

1. The plane of the coil was perpendicular to the direction of magnetic field so torque would be 0 because cos90 = 0

2. coils not in contact with commutator

3. no power source

 

[Komaticom]

1. coils are mongilated.
2. brushes ain't graphite.
3. no wires touching bushes, only a rod. No current will flow

Whoever made this motor deserves a spanking with a rusty-nail plank of wood.

 

[SeDaTeD]

1. Coils wound in the wrong direction/plane
2. coils not connected to commutator
3. no power supply

 

[Komaticom]

3. no power source

Debatable. Brushes lead into the block. Conducting wires might be in the block, leading out to a power source. The diagram might omit that, because the question focuses on the visible parts, i.e. magnets, armature, coil, brushes.

Did anyone say anything about the end pins?

 

[ShaunSmith]

there is no power supply, kthxbi.

 

[ramanij]

did any one see how one magnet was on the ledge(platform where the rotor and stuff was ) while another amgnet was not on the ledge

or am i jsut seeing things

 

[gordo]

you're seeing things

 

[mr_guy99493]

ok, magnets were fine

| N..............| | N..............|
therefore there is a south pole in the middle, and makes a nice little magnetic field.

1. the coils were NOT connected to the commutator
2. there was NO power supply
3. the coil was wound around the armature 25 times in one direction, then it was reversed and wound around 25 times in the other direction. the resultant torque from both sides of the armature is zero as they act in opposite directions.

/// <- these are windings

|\\\\\\\\\\____//////////| thats what it looked like, well, but hand drawn

so each side of the armature opposes the other


edit: hmm, the power supply one seems a bit iffy, and retrospectively i think that the commutator was pi/2 out of phase from the coils.

 

[poijse]

why can't u have a copper connection?! copper is a conductor, wires are usually made out of copper.

there is nothign wrong with using copper except it would ware faster, and perhaps create more friction.

using coper is not wrong...

 

[Komaticom]

Yes well, the right way to build a motor is use graphite brushes, not copper. Copper is used in the coil.

The question stated that you "identify" 3 flaws of the moron's motor. Using inappropriate or inefficient material is a flaw. So is a block of wood for an armature.

There is no need to describe the flaws, just state them. I circled the word "identify" in the question just in case the examiner feels like not giving me marks for not explaining my answer.

 

[mr_guy99493]

adamb, it is not that there is a misunderstanding of forces and torque, the forces acting on either side of the armature are in the same direction, giving no torque, due to the reversal of the direction of the windings