Phy 202
Your 'question form' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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Professor, I have 4 questions regarding the upcoming test for phy 202 3 are from the test and one is just a quesiton:
1) can you explain right hand rule and how we determine if a particle will move clockwise for counter clockwise?
Hold your right hand straight out so that the fingers point in the direction of the current. (If you have a moving charge, as in this case, then if the charge is positive its direction of the velocity is the direction of the current; if the charge is negative then the direction of the current is the direction directly opposite the velocity.)
Keeping your fingers in the direction of the current, rotate your hand so when you bend your fingers to make a 90 degree angle with your palm, they will point in the direction of the magnetic field.
When you bend your fingers in this manner, your thumb will point in a direction perpendicular to the original direction of your fingers, and to the direction of your bent fingers. This will be the direction of the force.
You can also search the Web. You will find numerous results for 'right hand rule'.
2)What will be the force on a segment of wire 14 cm long, carrying a current of 19 amps, in the presence of a .0009 Tesla magnetic field directed at an angle of 30 degrees with the segment? If the current is directed along the positive x axis and the field direction has no x component but makes its 30 degree angle with the z axis by having a y component in addition to the z component, what will be the direction of the force?
?????: This questions shouldnt be that hard but I cant get it. I think i am lacking on what formulas I am supposed to use. How can you find force if we are given length, current, mag field, but no radius?
Check out Introductory Problem Set 4, the last two problems, which explain the basic relationship
F = ( I * L ) * B * sin(`theta).
I will of course be glad to answer questions related to the explanations given there, or anywhere else in the problem sets.
3)A straight wire segment is .9 cm long and carries current 11 amps. A vector from the center of the segment to point P makes an angle of 55 degrees with a perpendicular to the segment and has length 22 cm. Find the magnetic of the field at P due to the segment.
?????: I dont understand how to incorporate the vector, I understand how to use length, radius, and amps to find force but how do i use the angle and and vector?
The first two problems in the Introductory Problem Set explain how to find the field due to a current segment at a point such that the vector lies perpendicular, then at an angle which is not perpendicular, to the segment.
Again I'll be glad to clarify anything you don't understand about that situation.
4)
Find an expression for the electric field strength at distance r from the axis of a capacitor consisting of two co-axial cylinders 3 meters long, with diameters 1.88 cm and 2.56 cm, with the inner cylinder carrying charge - 14.7 `microCoulombs and the outer cylinder carrying charge + 14.7 `microCoulombs. You will find three expressions, depending on whether r is less than 1.88 cm, greater than 2.56 cm or between the two.
• Estimate the average electric field between the cylinders, then determine the approximate work done per unit charge to move a charge from the inner cylinder to the outer. (University Physics students find the exact amount of work, using an integral).
• What is the voltage between the cylinders?
• What is the capacitance of this capacitor?
• What would be the approximate magnitude of the effect on the work, voltage and capacitance if the inner cylinder was not changed, but the outer cylinder shrunk in such a way as to be 10 times closer to the inner?
I honestly have no idea where to even start with this. Can you please just point me in the right direction
The last three problems in Introductory Problem Set 1 address the flux model and how it relates to various situations, including this one.
An imaginary cylinder with radius r between 1.88 cm and 2.56 cm encloses the charge of the inner cylinder. This allows you to determine the electric field at a point between the two cylinders.
An imaginary cylinder with radius r greater than 2.56 cm encloses the charges of both cylinders.
First check out the Introductory Problems, then see if you can apply that information to this situation. You'll probably have questions, which I'll be glad to answer.
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These seem to be my only huge questions right now. I tried to order them from ones i pretty much almost get to ones i have no idea about. Thanks for the help!
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See my notes, some of which refer you to existing documents. You'll probably have additional questions, but this should get you started.
Phy 202
Your 'question form' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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I also dont understand this question:
A long straight wire carries charge with density 8 `microCoulombs / meter. Describe a cylinder you would construct to find the field at distance 2.8 cm from the wire. Use this cylinder to find the field.
where is the section on these cylinders? did i miss this?
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The last three problems in Introductory Problem Set 1 address the flux model and is applications, including applications to this situation.
As before, I'll be glad to answer questions related to those problems and solutions.