I’m studying for my Physics class and need an explanation.
Q1. Calculate the force between two flat circular coils each containing 10 turns of wire and carrying 5 A of current in the same direction of circulation, have mean radii of 0.2 m and are placed coaxially 0.01 m apart.
Q2. A piece of ferromagnetic material with constant relative permeability 5000 is placed in a uniform magnetic field. The material is in the shape of a spheroid and is placed with its longest axis parallel to the field. What is the ratio of the flux density B inside the body to the original flux density outside the body when the axial ratio of the spheroid is:
- 1:1 (a sphere),
- 5:1 (a prolate spheroid)
- 100:1 (also a prolate spheroid)
- Q 3. Describe how the translational force on a magnetic material is related to the magnetic field and the properties of the material. The mass of a sample of paramagnetic material is being determined using a conventional force balance (i.e., by measuring its weight). However, in this case there is a magnetic field of strength 106 A.m-1 with a vertical field gradient of 2·107 A.m-2 present. If the susceptibility of the material is 4·10-4 calculate the force on the sample and hence the error in the measured mass.
- Q 4. Iron has a magnetic moment of 2.22 Bohr magnetons per atom and a density of 7.87·103 kg.m-3. Calculate the expected magnetization of iron at 0 K and describe any assumptions that you have made. How would you expect this magnetization of iron to vary as temperature is increased. How does the number of Bohr magnetons per atom change from 0 K to 300 K. Why does a piece of iron typically not exhibit high magnetization at room temperature (unless it has been “magnetized”)?
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