Motor Effect - Exam Question (1 Viewer)

[Kukudas]

Q. In your Physics course you have performed a first-hand investigation to demonstrate the motor effect. Explain how your results demonstrated that effect (4mark)

can any1 please give me 4 mark response.!!
thank you very much!!

 

[ianc]

did you do that current balance experiment?



its the one where a rectangle of wire is placed inside a solenoid, with half of it sticking out......a bit like a see-saw

http://www.sciencefirst.com/pctr/10146.jpg (the part with the rectangle of wire is placed inside the solenoid, the part with the metal cap is outside)

anyway....current is run through the solenoid to produce a magnetic field, and also another current is run through the see-saw, such that at the very end of the rectangle, some of the current is flowing perpendicular to the magnetic field.

so this will produce a force, and the see-saw will tilt slightly up or down. If you balance small weights on the end of the see-saw, you can calculate the magnitude of the force (ie the motor effect)


hopefully that gave you an idea.....to get the four marks you will need to briefly outline the experiment, and explain how current is made to travel perpendicular to a magnetic field. then say how that, due to the motor effect, there was a force acting on the conductor which moved the see-saw (sorry, call it a current balance). and then finally you could measure that force against a known quanity - weight due to gravity.

so keep it logical and clear, and you should get 4 marks....remember the keyword "explain" means to relate cause and effect.


I hope that made some sense! Good luck!

 

[Forbidden.]

did you do that current balance experiment?



its the one where a rectangle of wire is placed inside a solenoid, with half of it sticking out......a bit like a see-saw

http://www.sciencefirst.com/pctr/10146.jpg (the part with the rectangle of wire is placed inside the solenoid, the part with the metal cap is outside)

anyway....current is run through the solenoid to produce a magnetic field, and also another current is run through the see-saw, such that at the very end of the rectangle, some of the current is flowing perpendicular to the magnetic field.

so this will produce a force, and the see-saw will tilt slightly up or down. If you balance small weights on the end of the see-saw, you can calculate the magnitude of the force (ie the motor effect)


hopefully that gave you an idea.....to get the four marks you will need to briefly outline the experiment, and explain how current is made to travel perpendicular to a magnetic field. then say how that, due to the motor effect, there was a force acting on the conductor which moved the see-saw (sorry, call it a current balance). and then finally you could measure that force against a known quanity - weight due to gravity.

so keep it logical and clear, and you should get 4 marks....remember the keyword "explain" means to relate cause and effect.


I hope that made some sense! Good luck!

^ Our one is different ... ... It's even more complicated.
I hope I can get away by not using my practical but another more simple practical, not in the Trials though ...

 

[idling fire]

The experiment my class did was just dangling a wire (in a circuit) from a retort stand, and moving a magnet around near the bottom to see it move a tiny bit. Simple and boring.

 

[Kukudas]

thank you all!

 

[Forbidden.]

The experiment my class did was just dangling a wire (in a circuit) from a retort stand, and moving a magnet around near the bottom to see it move a tiny bit. Simple and boring.

Care to give us ideas ?

 

[idling fire]

Care to give us ideas ?

What kind of ideas? *raises eyebrow*

 

[Forbidden.]

What kind of ideas? *raises eyebrow*

Simple is best !
Your experiment sounds a LOT simpler than ours, I'd prefer to use yours, a brief outline or the method/results will do ...

 

[idling fire]

*Hold bar magnet near the end of the wire and turn on the power pack.
Observation - the wire moved a small distance from its original position when current began to flow through wire, and stayed there)
*Turn off powerpack - wire moves back to original position

So that's basically our demonstration of the motor effect (since current carrying wire moved in presence of magnetic field).

Part 2: Then we also varied field strength (used stronger magnets), changed amount of current, changed direction of current and direction of magnetic field, and the the length of wire within the field.
Admittedly, the field strength and wire length alterations are a bit dodgy, because one can hardly be changed without the other in the classroom situation.

From part 2 we observed the greatest movement with greater I, stronger B, largest wire length and when the magnetic field was perpendicular to the current. (As predicted from the equation F=BIlsinθ )