How Is Current Calculated for Rotational Equilibrium in a Magnetic Field?

In summary, the conversation discusses a uniform bar with a mass of 0.0180 kg and a length of 30.0 cm that is pivoting without friction about an axis at point a. The bar is under the influence of a gravitational force in the -y direction and a uniform magnetic field with a magnitude of 0.350 T directed into the page. The question at hand is the necessary current, I, for the bar to be in rotational equilibrium at an angle of 60.0 degrees above the horizontal. The formula used is F = qv x B and dF = Idl x B, with the solution found by equating mg(L/2 cos theta) to IB L^2/2 and solving
  • #1
TheBigDig
65
2
1. A uniform bar has mass 0.0180 kg and is 30.0cm long. It pivots without friction about an axis perpendicular to the bar at point a (as seen in the diagram). The gravitational force on the bar acts in the −y-direction. The bar is in a uniform magnetic field that is directed into the page and has magnitude 0.350 T . What must be the current I in the bar for the bar to be in rotational equilibrium when it is at an angle 60.0o above the horizontal? 2. F = qv x B
dF = Idl x B3. I've attempted to just plug in the values using the numbers given in the question but I'm unsure how to account for the angle using the above formulae.
Young.Ch27.Pr72.Fig.P27.72.eps.jpg
 
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  • #2
Draw a free-body diagram. Show all the forces acting on the bar.
 
  • #3
Thanks. Found it by equating mg(L/2 cos theta) to IB L^2/2 and solving for I.
 

Related to How Is Current Calculated for Rotational Equilibrium in a Magnetic Field?

1. What is the purpose of finding current through a bar?

The purpose of finding current through a bar is to determine the flow of electric current through a conductive material, such as a metal bar. This information can be used to calculate the resistance, voltage, or power of the material.

2. How do you find the current through a bar?

The current through a bar can be found using Ohm's law, which states that current (I) is equal to the voltage (V) divided by the resistance (R). This can be represented by the equation I = V/R. By measuring the voltage and resistance of the bar, the current can be calculated.

3. What factors affect the current through a bar?

The current through a bar is affected by several factors, including the material and thickness of the bar, the temperature of the bar, and the voltage applied to the bar. Additionally, the presence of any impurities or defects in the material can also affect the flow of current.

4. How is the current through a bar measured?

The current through a bar can be measured using a multimeter, which is a device that can measure voltage, resistance, and current. The multimeter is connected to the ends of the bar, and the current reading is displayed on the device.

5. What are some applications of finding current through a bar?

Finding current through a bar has many practical applications, such as in electrical circuits and systems. It is also used in various industries, such as electronics, transportation, and manufacturing, to ensure the proper functioning and safety of equipment and devices.

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