Calculating Direction of Current with Left-Hand Rule: Magnetic Fields Homework

In summary, at a certain point on Earth's surface, the horizontal component of the magnetic field is 1.8 * 10^-5 T and a 2m long wire with a mass of 1.5g placed on a horizontal wooden bench in an east-west direction is lifted off the surface when a large current is passed through it. The direction of the current in the wire is east. The left-hand rule is used to determine the direction of the current, even though the direction of the vertical component of the magnetic field is unknown. This is because the only force acting on the wire is in the upward direction, which is related to the horizontal magnetic field. The direction of Earth's magnetic field is also important in determining the
  • #1
jsmith613
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Homework Statement



At a certain point on the Earth's Surface the horizontal component of the Earth's magnetic field is 1.8 * 10^-5 T. A straight piece of wire 2m long and 1.5g lies on a horizontal wooden bench in an east-west direction. When a very large current flows momenterily in the wire it is JUST enough to cause the wire to lift off the bench surface.
State the direction of the current in the wire.

Homework Equations


NONE
Use left-hand rule

The Attempt at a Solution


What I don't understand is how we can use the left hand rule given the information. We don't know the direction of the magentic field (we were only given the horizontal componenet - i.e there is a vertical component too)

How is this done
(if it helps the answer is east)
 
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  • #2
does it have anything to do with the fact that the only magnetic field is horiztonal because the only force is up
 
  • #3
What do you know about the direction of Earth's magnetic field ?
 

1. How do I determine the direction of current using the left-hand rule?

The left-hand rule is used to determine the direction of current in a conductor placed in a magnetic field. To use this rule, point your left thumb in the direction of the current and your fingers in the direction of the magnetic field. The direction in which your palm faces is the direction of the force on the conductor, and therefore the direction of the current.

2. What is the purpose of using the left-hand rule?

The left-hand rule is used to determine the direction of current in a conductor in a magnetic field. This is important in understanding how electric currents and magnetic fields interact and can help in predicting the behavior of electric motors, generators, and other electromagnetic devices.

3. Can the left-hand rule be used for any type of current?

The left-hand rule can be used for any type of current, including direct current (DC) and alternating current (AC). However, it is important to note that the direction of the current may change in an AC circuit, so the direction of the magnetic field and the direction of the force on the conductor may also change.

4. How do I apply the left-hand rule to a specific scenario?

To apply the left-hand rule to a specific scenario, you will need to know the direction of the current and the direction of the magnetic field. Once you have this information, use your left hand to point your thumb in the direction of the current and your fingers in the direction of the magnetic field. The direction in which your palm faces is the direction of the force on the conductor.

5. Are there any limitations or exceptions to the left-hand rule?

The left-hand rule is a simplified way of determining the direction of current in a conductor in a magnetic field. It is based on the principles of electromagnetism and is generally accurate. However, there may be some exceptions or limitations in certain scenarios, such as when dealing with complex magnetic fields or non-uniform currents. In these cases, other methods may need to be used to determine the direction of current.

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