Induced EMF and long steel beam

In summary, a steel beam with a length of 5.97 m is dropped from a height of 6.82 m by a construction crane over a region with a horizontal component of the Earth's magnetic field of 12.2 \mu T. The acceleration of gravity is 9.8 m/s^2. Using the equation for motional emf and the speed of the beam as it reaches the ground, the induced emf can be calculated in units of mV.
  • #1
Punchlinegirl
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A 5.97 m long steel beam is accidentally dropped by a construction crane from a height of 6.82 m. The horizontal component of the Earth's magnetic field over the region is 12.2 [tex]\mu T[/tex]. The acceleration of gravity is 9.8 m/s^2. What is the induced emf in the beam just before impact with the Earth, assuming its long dimension remains in a horizontal plane, oriented perpendicularly to the horizontal component of the Earth's magnetic field? Answer in units of mV.

I know that E= change in flux/change in time
To get the change in time I used the equation
x(t)= x_o +v_o*t +.5 gt^2
where x_o=v_o=0
and x(t)= 6.82 m.
solving for t gave me .834 s.
Then for the flux I think it's just B*L= 72.8... but I don't think that's right...
Can someone please help me?
 
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  • #2
review something called "motional emf." THere is a variation of the emf formula for a straight conductor moving through a magnetic field in terms of its speed. Then, all you need to do is find the speed of the bar as it reaches the ground.
 
  • #3
I got it... Thanks!
 

Related to Induced EMF and long steel beam

1. How is induced EMF generated in a long steel beam?

Induced EMF, or electromotive force, is generated in a long steel beam when it is subjected to a changing magnetic field. This changing magnetic field can be created by moving the beam through a stationary magnetic field or by changing the strength of the magnetic field around the beam.

2. What factors can affect the magnitude of induced EMF in a long steel beam?

The magnitude of induced EMF in a long steel beam can be affected by several factors, including the strength of the magnetic field, the speed at which the beam is moving through the field, and the length and thickness of the beam. Additionally, the angle between the direction of the beam's motion and the direction of the magnetic field can also impact the magnitude of induced EMF.

3. How is induced EMF different from regular EMF?

Induced EMF is different from regular EMF in that it is created by a changing magnetic field, whereas regular EMF is created by a battery or other source of electric potential. Induced EMF is also typically temporary and only exists as long as the changing magnetic field is present, whereas regular EMF can be constant.

4. What are some practical applications of induced EMF in long steel beams?

Induced EMF in long steel beams has various practical applications, including in electromagnetic induction devices, such as generators, motors, and transformers. It can also be used in sensors and measuring devices, as well as in electromagnetic braking systems for trains and other vehicles.

5. How can induced EMF in long steel beams be minimized or controlled?

To minimize or control induced EMF in long steel beams, one can use shielding materials, such as non-magnetic metals, to reduce the strength of the magnetic field around the beam. Additionally, changing the speed or direction of the beam's motion can also help to control the induced EMF. For certain applications, such as in generators, the shape and orientation of the beam can also be designed to minimize induced EMF.

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