Magnetic fields - which direction

In summary: Yes, the maximum EMF could be achieved by traveling ppd to the horizontal componenet of the Earth's magnetic field.
  • #1
jsmith613
614
0

Homework Statement


If a flat wire lies in a north-south direction will the MAXIMUM magnetic force be felt if the field lies either in a east-west direction OR an up-down direction (i.e: ppd to the direction of the current?)??


Homework Equations





The Attempt at a Solution


I know that the maximum magnetic force is felt when the current and field are perpendicular
BUT does it matter which plane the magnetic field is in so long as it is perpendicular?

Also, in exams will it be clear which direction the field is in
(e.g: they might say it acts at a 40 degree angle to the horizontal)
therefore if the current is straight ahead I calculate the component perpendicular to the direction of the current to find the force??
 
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  • #2
jsmith613 said:

Homework Statement


If a flat wire lies in a north-south direction will the MAXIMUM magnetic force be felt if the field lies either in a east-west direction OR an up-down direction (i.e: ppd to the direction of the current?)??


Homework Equations





The Attempt at a Solution


I know that the maximum magnetic force is felt when the current and field are perpendicular
BUT does it matter which plane the magnetic field is in so long as it is perpendicular?

Also, in exams will it be clear which direction the field is in
(e.g: they might say it acts at a 40 degree angle to the horizontal)
therefore if the current is straight ahead I calculate the component perpendicular to the direction of the current to find the force??

I think the key to this question is the use of the word "flat" in describing the current-carrying wire. That shape should make the maximum B-field happen in only one of the two choices given...
 
  • #3
berkeman said:
I think the key to this question is the use of the word "flat" in describing the current-carrying wire. That shape should make the maximum B-field happen in only one of the two choices given...

so you're saying that if I had some height as well then it would exclude the up-down direction?

so a block facing in an east west direction would need a mag field in a south-north direction??

also what would happen with an aerial
it has height but basically no depth.
"a car with a vertical aerial 1.2m is moving at 35 m/s. The horizontal componenet of the Earth's magnetic field is 22 * 10-6T. Find the emf induced"

they give me the horizontal compoenent but surely I could also use the forward backward componenet as that too is ppd to the aerial?
 
  • #4
jsmith613 said:
so you're saying that if I had some height as well then it would exclude the up-down direction?

so a block facing in an east west direction would need a mag field in a south-north direction??

Sorry, I'm not understanding what you are saying.

What I was saying was that if you draw a flat wire of some width, going in the N-S direction, then at the same radius R away from the wire, you will get a slightly different B field if you are out at the side (say on the East side, where the B field points up and down), or up towards you (where the B field points East and West).
 
  • #5
berkeman said:
Sorry, I'm not understanding what you are saying.

What I was saying was that if you draw a flat wire of some width, going in the N-S direction, then at the same radius R away from the wire, you will get a slightly different B field if you are out at the side (say on the East side, where the B field points up and down), or up towards you (where the B field points East and West).

well what I was trying to understand was how the direction of the mag field is important

going back to this question:
a car with a vertical aerial 1.2m is moving at 35 m/s. The horizontal componenet of the Earth's magnetic field is 22 * 10-6T. Find the emf induced

would the MAXIMUM EMF only be possible if I was traveling ppd to the horizontal compoenent of the Earth's mag field (assuming this was the ONLY component)

therefore could I either be traveling straight ahead OR upwards to achieve this maximum EMF??
 

1. What is a magnetic field?

A magnetic field is an invisible force that is created by moving electric charges, such as the flow of electrons. It is present around magnetic materials and can exert a force on other magnetic materials or on moving electric charges.

2. How is the direction of a magnetic field determined?

The direction of a magnetic field is determined by the direction in which a compass needle points when placed in the field. The north pole of a compass needle will always point towards the direction of the magnetic field lines.

3. What is the difference between magnetic field strength and magnetic field direction?

Magnetic field strength refers to the intensity or power of a magnetic field, while magnetic field direction refers to the orientation or path of the magnetic field lines. The strength of a magnetic field can vary, but the direction remains constant.

4. Can the direction of a magnetic field be changed?

Yes, the direction of a magnetic field can be changed by changing the orientation of the magnetic material, such as by rotating a magnet or changing the direction of current flow in a wire.

5. How are magnetic fields used in everyday life?

Magnetic fields have a wide range of applications, from powering electronic devices such as speakers and motors, to medical imaging technologies like MRI. They are also used in transportation systems such as trains and levitating trains, and in data storage devices like hard drives.

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