Solving Lenz's Law Problem for Midterm: Get Help Now!

In summary, the question is about finding the average induced emf in a 213 turn coil when a patient inhales, given the change in area of the coil, the Earth's magnetic field, and the time it takes for the patient to inhale. The suggested equation to use is Faraday's law, which involves finding the derivative of the magnetic flux and solving for the change in area. This yields the answer for the average induced emf.
  • #1
jenner7231
2
0
I'm reviewing for a midterm and I'm stuggling with this question because I'm not sure what equation would be appropirate. I believe that it is Lenz's Law, but I need some suggestions as to what equation to use.

Question:
To monitor the breathing of a hospital patient, a thin belt is girded around the patient's chest. The belt is a 213 turn coil. When the patient inhales, the area encircled by the coil increases by 39.0 cm2. The magnitude of the Earth's magnetic field is 50.0 µT and makes an angle of 28.0° with the plane of the coil. Assuming that a patient takes 1.80 s to inhale, find the average induced emf in the coil during this time.

any help would be appreciated!
 
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  • #2
Look up Faraday's law. That's the one you need.
 
  • #3
Yeah, Doc Al is correct.

You know that emf= - (d/dt) (magnetic flux)

and since n=213, B=50x10^-6, and theta=62 degrees (remember, you're finding the angle between the area vector A, which is perpendicular to the loop, and B), we can solve.

the n, cos(theta), and B all come out of the derivative, leaving dA/dt, which is trivial to solve. And thus, you have the answer.:smile:
 

Related to Solving Lenz's Law Problem for Midterm: Get Help Now!

1. What is Lenz's Law and why is it important?

Lenz's Law is a fundamental law of electromagnetism that describes the direction of current induced in a conductor by a changing magnetic field. It is important because it helps us understand and predict the behavior of electromagnetic forces, which are crucial in many technological applications.

2. How do you solve a Lenz's Law problem?

To solve a Lenz's Law problem, you need to follow these steps:

  • 1. Identify the direction of the changing magnetic field.
  • 2. Determine the direction of the induced current using Lenz's Law (the induced current will always oppose the change in the magnetic field).
  • 3. Use the right-hand rule to determine the direction of the magnetic force on the conductor.
  • 4. Apply the right-hand rule again to determine the direction of the magnetic force on any other nearby conductors.
  • 5. Use the equations for electric and magnetic forces to solve for any unknown quantities.

3. Can you give an example of a Lenz's Law problem?

Sure, here's an example: A loop of wire is placed in a magnetic field that is directed into the page. The field is then decreased in strength. What is the direction of the induced current in the loop?

4. What are some common mistakes when solving Lenz's Law problems?

Some common mistakes when solving Lenz's Law problems include forgetting to use the right-hand rule, not considering the direction of the changing magnetic field, and mixing up the direction of the magnetic force on the conductor and the induced current.

5. Are there any real-world applications of Lenz's Law?

Yes, Lenz's Law has many real-world applications, including generators, motors, transformers, and induction heating. It is also used in devices like magnetic levitation trains and magnetic braking systems.

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