Question about magnetic fields

In summary, the conductor must have a current of 302 mA in order for the tension in the supporting wires to be zero when the magnetic field is 2.60 T into the page. This can be calculated using the formula F=IL x B, where F is the magnetic force per unit length, I is the current, and B is the magnetic field. The weight per unit length of the conductor is 0.784 N/m, which must be equal to the magnetic force in order for there to be zero tension in the wires. Therefore, the current can be found by dividing the weight per unit length by the magnetic field strength.
  • #1
andrew410
59
0
A conductor suspended by two flexible wires as in the figure below has a mass per unit length of 0.0800 kg/m.

What current must exist in the conductor in order for the tension in the supporting wires to be zero when the magnetic field is 2.60 T into the page?

Figure: http://east.ilrn.com/books/sepsp06t/pse6e.29.14p.e.jpg

I know you have to use the formula F=IL x B to get the current but I don't know how to put it all together...
I think the force is the tension so you can make that zero. I don't know how to get the length because it only gives you the mass per unit length.
Maybe I'm doing this wrong...I don't know...
Please help me! Thanks in advance! :)
 
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  • #2
The magnetic force (F) per unit length (L) is:
F/L = BI

It's weight (W) per unit length is:
W/L = mg/L
= (m/L)*g
= 0.08*9.8 N/m
= 0.784 N/m

To have zero tension in the supporting wires, the conductor's magnetic force must cancel out it's weight (i.e. W=F)

BI = 0.784 N
-> I = 0.784/2.6 A
= 302 mA (current must go from left to right, using the right-hand rule)
 
  • #3
thx for the help and the quick response! :)
 

FAQ: Question about magnetic fields

What is a magnetic field?

A magnetic field is an invisible force field created by moving electric charges, such as electrons. It can be visualized as lines of force that form around a magnet or a current-carrying wire.

How are magnetic fields created?

Magnetic fields are created by moving electric charges, such as those found in magnets or in currents of electricity. The movement of these charges creates a force that can attract or repel other magnetic materials.

What are the properties of a magnetic field?

A magnetic field has both direction and strength. The direction of the field is determined by the direction of the moving charges, while the strength is determined by the amount of charge and the distance from the source.

How are magnetic fields measured?

Magnetic fields are measured using a device called a magnetometer, which can detect the strength and direction of a magnetic field. The unit of measurement for magnetic fields is the Tesla (T), with smaller units such as the Gauss (G) also commonly used.

What are some real-life applications of magnetic fields?

Magnetic fields have many practical uses, such as in electric motors, generators, and speakers. They are also used in medical imaging techniques such as MRI, as well as in compasses and navigation systems. Magnetic fields are also important in the study of celestial bodies, as they play a crucial role in the formation of stars and planets.

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