# CLASS 12 – PHYSICS-- Chapter 6: PHYSICS OF SOLID

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1. ## CLASS 12 – PHYSICS-- Chapter 6: PHYSICS OF SOLID

CLASS 12 – PHYSICS

Chapter 6: PHYSICS OF SOLID

Q1. Give five important mechanical properties of solids.

Ans. The mechanical properties of material are connected with its behavior under the action of external forces. The important mechanical properties of solid are strength, stiffness, ductility and toughness.

Q2. Distinguish among crystalline, amorphous and polymeric solids.

CRYSTALLINE SOLIDS:
In the crystalline solids, the atoms, molecules or ions are arranged in regular repetitive manner forming a three dimension structure (lattice). The metals like copper, iron and zinc are crystalline solid.
AMORPHOUS SOLID:
The word amorphous means without structure. The amorphous solid have no regular arrangement of their atoms, molecules or ions. Ordinary glass is a amorphous solid.
POLYMERIC SOLID:
Polymeric solid may be more or less solid material with a structure which is intermediate between order and disorder. The molecular structure of polymers is more order than liquid and less order than solid. The polymers are formed by combining simple molecules into massive rubber, polyester and nylon.

Q3. State the general form of Hooke’s law of elasticity.

Ans. According to Hook’s law for small deforming force the stress is directly proportional to strain
Stress α strain
Stress = constant x strain
Stress/strain = constant
This constant is called elastic constant or modulus of elasticity modulus of elasticity modulus of
Elasticity = stress/strain.

Q4. Define shear stress, shear strain and the shear modulus of elasticity.

Ans.
Shear stress:
When the stress changes the shape of the body it is called shear stress.
Shear strain:
The angle through which the edge of the cubic body displaces is called shear strain.
Shear modulus:
The ratio of shear stress to shear strain is called shear modulus
Shear modulus = shear stress/ shear strain

Q5. How is P-type semiconductor prepared?

Ans. The P-type semiconductor is prepared by adding trivalent impurities in the pure germanium or silicon.

Q6. How is an n-type semiconductor prepared?

Ans. The n-type semiconductor is prepared by adding pentavalent impurities in the pure germanium or silicon.

Q7. Explain, briefly, the concept of elasticity of a solid.

Ans. Any change produced in shape, length or volume of solid which is subjected to some external force is called deformation. The force required to deform a solid is called deforming force. When the deforming force is removed, the solid tends to resume its original state. The property is removed, the solid tends to resume its original state. the property of a solid due to which it regain its original shape, after the removal of external deforming force is called elasticity off a solid.

Q8. What is superconductivity?

Ans. The conductive with almost zero resistance is called supper conductor and the phenomenon is called super conductivity.

Q9. Distinguish between paramagnetic and diamagnetic materials.

Ans. The substances in which in atoms, there is resultant magnetic field due to orbital and spinning motion of electron are called paramagnetic substances. The example of which are manganese, aluminum and platinum. The magnetic fields due to orbital motion and spinning motion when added is zero, such substances are called diamagnetic substances. The examples of which are bismuth, lead, gold and antimony.

Q10. Explain the existence of magnetic domains in ferromagnetic materials.

Ans. Substances in which the atoms co-operate with each other in such way as the show a strong magnetic effect in the presence of external field are ferromagnetic substances. In ferromagnetic substances like iron the individual atom.

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2. ## Re: CLASS 12 – PHYSICS-- Chapter 6: PHYSICS OF SOLID

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