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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: Flaming_Arrow on July 01, 2009, 12:50:24 pm

Title: Help with unit 4 questions
Post by: Flaming_Arrow on July 01, 2009, 12:50:24 pm
i am really horrible with this topic

can someone explain how to do this?
Title: Re: Help with unit 4 questions
Post by: Flaming_Arrow on July 01, 2009, 01:07:31 pm
shouldn't the force of the magnetic field go west?

Title: Re: Help with unit 4 questions
Post by: methodsboy on July 01, 2009, 01:11:58 pm
shouldn't the force of the magnetic field go west?


the answer is east init? it would be west if you used ur left hand.
Title: Re: Help with unit 4 questions
Post by: dekoyl on July 01, 2009, 01:23:12 pm
For the second post of yours, I think the force should go east if you use the right-hand-slap rule.
Magnetic field into the page, current down, and your palm is facing the right (east).

I had (and still do) a lot of trouble with it. Maybe the left-hand rule (not sure of the name the book uses) may work better for you.
Title: Re: Help with unit 4 questions
Post by: Flaming_Arrow on July 01, 2009, 01:47:21 pm
For the second post of yours, I think the force should go east if you use the right-hand-slap rule.
Magnetic field into the page, current down, and your palm is facing the right (east).

I had (and still do) a lot of trouble with it. Maybe the left-hand rule (not sure of the name the book uses) may work better for you.

for the right hand slap rule, doesnt the palm have to be facing down?
Title: Re: Help with unit 4 questions
Post by: kurrymuncher on July 01, 2009, 02:45:46 pm
The magnetic field is towards the page and the current is facing down, so your palm should be facing east. Hold your right hand up,, with your thumb facing up. rotate it 180 degrees, so your thumb is facing down. Now point the tips of your fingers to the page. You should have your palm facing east.

lol, hope u can understand this.
Title: Re: Help with unit 4 questions
Post by: TrueTears on July 01, 2009, 03:03:42 pm
i am really horrible with this topic

can someone explain how to do this?

for a)

at Z it is going into the page. (thumb points up at a tangent to the wire, your fingers curve into the page)

at Y it goes into the page (same principle)

at X it goes into the page (again point your thumb down the page now and your fingers should be curved into the page)

at W it comes out of the page (image what happens when your curve your fingers in at X? it will come OUT of the page at W)

b) W and X are both into the page (again thumb points in direction of current, look where your fingers curve into)

Now Y and Z are outside the solenoid, remember in a solenoid the NET magnetic field created exists all the way around the whole solenoid.

first let's find out where the net magnetic field is.

take any one of the coils in the solenoid, thumb points in direction of current, now as you curve your fingers around the wire, they curve from the left to the right INSIDE the solenoid.

So net magnetic field is going from LEFT to RIGHT inside the solenoid.

But Y and Z are outside, consider the left of the solenoid as south and the right as north.

Now mag fields always go from north to south, extend the mag fields outside the solenoid and you see both at Y and Z the mag field goes from RIGHT to LEFT.
Title: Re: Help with unit 4 questions
Post by: TrueTears on July 01, 2009, 03:10:16 pm
shouldn't the force of the magnetic field go west?


Force goes east.

cross means into the page.

Right hand slap rule.

Thumb point down the page. Your fingers should point into the page. Now slap the wire with your palm, where did you slap it? East.

Hence force is to the east.