Bar Magnet Torque problem

In summary, a bar magnet experiences a torque of 0.075 Nm when perpendicular to a 0.50 T external magnetic field. The strength of its on-axis magnetic field at a point 20 cm from the center of the magnet is 3.75 x 10^-6 T. This was calculated using the equations \tau = \vec{\mu} B sin\vartheta and B = \frac{\mu_0}{4 \pi} \frac{2 \vec{\mu}}{z^3}.
  • #1
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Homework Statement



A bar magnet experiences a torque of magnitude 0.075 Nm when it is perpendicular to a 0.50 T external magnetic field. What is the strength of the bar magnet's on-axis magnetic field at a point 20 cm from the center of the magnet?

Homework Equations



[tex]\tau = \vec{\mu} B sin\vartheta[/tex]

[tex]B = \frac{\mu_0}{4 \pi} \frac{2 \vec{\mu}}{z^3}[/tex]

The Attempt at a Solution



since its perpendicular, sin90 = 1 so:

[tex]\tau = \vec{\mu} B \Rightarrow \vec{\mu} = \frac{\tau}{B} = \frac{0.075}{0.5} = 0.15[/tex]

[tex]B = \frac{\mu_0}{4 \pi} \frac{2 \vec{\mu}}{z^3} = 10^-7 \frac{2(0.15)}{0.2^3} = 37.5 T[/tex]

Any help would be appreciated. Thank You.
 
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  • #2
i don't get it.. what is ur problem as such? as far as i see it, you have already solved it...
 
  • #3
I inputted 37.5 and it was wrong.
 
Last edited:
  • #4
Considering that 37.5 T is 750,000 times greater than that on the surface of the earth, you might want to recalculate that value.
 
  • #5
I see what I did wrong. I forgot to multiply it by 10^-7 so the answer should be 3.75 x 10^-6, and it is.
 
Last edited:

1. What is a bar magnet torque problem?

A bar magnet torque problem refers to a physics problem that involves determining the torque, or rotational force, experienced by a bar magnet in a magnetic field. This type of problem typically involves calculating the magnitude and direction of the torque based on the properties of the magnet and the characteristics of the magnetic field.

2. How do I solve a bar magnet torque problem?

To solve a bar magnet torque problem, you will need to use the formula for torque (T = r x F), where r is the distance between the axis of rotation and the point where the force is applied, and F is the force applied. You will also need to consider the magnetic moment of the bar magnet and the strength and direction of the magnetic field. It may also be helpful to draw a diagram to visualize the problem.

3. What factors affect the torque experienced by a bar magnet?

The torque experienced by a bar magnet in a magnetic field is affected by several factors, including the strength and direction of the magnetic field, the magnetic moment of the bar magnet, and the angle between the magnet's magnetic moment and the direction of the magnetic field. The distance between the axis of rotation and the point where the force is applied also plays a role in determining the torque.

4. Can a bar magnet experience zero torque in a magnetic field?

Yes, a bar magnet can experience zero torque in a magnetic field. This occurs when the magnetic moment of the bar magnet is aligned with the direction of the magnetic field, resulting in no perpendicular component of the magnetic force and thus no torque. This is known as equilibrium or stable magnetic orientation.

5. Are there any real-world applications of bar magnet torque problems?

Yes, bar magnet torque problems have real-world applications in various fields, including engineering, physics, and geophysics. For example, they are used in the design of motors and generators, magnetic compasses, and in studying the Earth's magnetic field. They can also be applied in medical imaging techniques such as magnetic resonance imaging (MRI).

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