Q1. The permeability of a magnetic material is 0.9983. Name the type of magnetic materials it represents.
Q2. In what way is the behaviour of a diamagnetic material different from that of a paramagnetic, when kept in an external magnetic field?
Q3. Depict the behaviour of magnetic field lines in the presence of a diamagnetic material.
Q4. Relative permeability of a material µr = 0.5. Identify the nature of the magnetic material and write its relation to magnetic susceptibility.
Q5. What is the characteristic property of a diamagnetic material?
Q6. If χ stands for the magnetic susceptibility of a given material, identify the class of material for which
(i) –1 ≤ χ < 0
(ii) 0 < χ < e (e stands for a small positive number)
Q7. Define magnetic susceptibility of a material. Name two elements, one having positive susceptibility and the other having negative susceptibility. What does negative susceptibility signify?
Q8. Depict the behaviour of magnetic field lines with (i) a diamagnetic material and (ii) a paramagnetic material placed in an external magnetic field. Mention briefly the properties of these materials which explain this distinguishing behaviour.
Q9. (a) How does a diamagnetic material behave when it is cooled to very low temperatures?
(b) Why does a paramagnetic sample display greater magnetisation when cooled? Explain.
Q10. The following figure shows the variation of intensity of magnetisation versus the applied magnetic field intensity, H, for two magnetic materials A and B:
(a) Identify the materials A and B.
(b) Why does the material B, have a larger susceptibility than A, for a given field at constant temperature?
Q11. Distinguish between diamagnetic and ferromagnetic materials in terms of (i) susceptibility and (ii) their behaviour in a nonuniform magnetic field.
Q12. Distinguish few magnetic properties of dia-, para- and ferro-magnetic substances in terms of (i) susceptibility, (ii) magnetic permeability and (iii) coercivity. Give one example of each of these materials.
Q13. (i) Write two characteristics of a material used for making permanent magnets.
(ii) Why is core of an electromagnet made of ferromagnetic materials?
Q14. Why should the material used for making permanent magnets have high coercivity?
Q15. (i) What are permanent magnets? Give one example.
(ii) What is the difference between an electromagnet and a permanent magnet? How is an electromagnet designed? State any two factors on which the strength of an electromagnet depends.