2005 paper m/c questions (1 Viewer)

[Graceofgod]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2005exams/pdf_doc/physics_05.pdf

Ok, I am having trouble with 2 of the multiple choice questions from this.

First, question 7. Is this just a poorly worded question?
I took it as meaning what direction is the current going in 0.0001 seconds after it starts turning.
I'm lost on this one.

<meta http-equiv="CONTENT-TYPE" content="text/html; charset=utf-8"><title></title><meta name="GENERATOR" content="OpenOffice.org 2.4 (Unix)"><style type="text/css"> <!-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } --></style> Question 9 is the other problem.
A full copper ring should have the slowest fall due to large eddy currents.
The cut copper ring will have a slightly slowed fall due to little eddy currents.
Then the plastic not slowed at all due to no eddy currents as it is not a metal.
However the answer says that the cut copper and the plastic arrive Simultaneously. How is that right..?

Any help appreciated

 

[WantToDoBetter]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2005exams/pdf_doc/physics_05.pdf

Ok, I am having trouble with 2 of the multiple choice questions from this.

First, question 7. Is this just a poorly worded question?
I took it as meaning what direction is the current going in 0.0001 seconds after it starts turning.
I'm lost on this one.

<META content="OpenOffice.org 2.4 (Unix)" name=GENERATOR><STYLE type=text/css> <!-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } --></STYLE>Question 9 is the other problem.
A full copper ring should have the slowest fall due to large eddy currents.
The cut copper ring will have a slightly slowed fall due to little eddy currents.
Then the plastic not slowed at all due to no eddy currents as it is not a metal.
However the answer says that the cut copper and the plastic arrive Simultaneously. How is that right..?

Any help appreciated

7​

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A single-turn coil of wire is placed in a uniform magnetic field B at right angles to the plane of the coil as shown in the diagrams. The coil is then rotated in a clockwise direction as shown.

Which of the following shows the direction of current flow in the coil as it begins to rotate?

Because it is an induced emf on the coil the current will flow in the opposite direction when applying the right hand palm rule. EG. Palm rule works for D but the current will be the other direction to this due to Lenz's Law. Therefore the answer is A. PS. Rlue out B and C straight away as the current is flowing in the same direction.


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[Graceofgod]

7​

A single-turn coil of wire is placed in a uniform magnetic field B at right angles to the plane of the coil as shown in the diagrams. The coil is then rotated in a clockwise direction as shown.

Which of the following shows the direction of current flow in the coil as it begins to rotate?

Because it is an induced emf on the coil the current will flow in the opposite direction when applying the right hand palm rule. EG. Palm rule works for D but the current will be the other direction to this due to Lenz's Law. Therefore the answer is A. PS. Rlue out B and C straight away as the current is flowing in the same direction.


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Ah, of course. Stupid me

Question 9 anyone?