Free Physics of Solids MCQs with Answers

1. The materials in which disordered structure of liquid is frozen are:

• A. Amorphous
• B. Crystalline
• C. Polycrystalline
• D. Quartz

Explanation: The materials in which the disordered structure of a liquid is frozen are typically referred to as amorphous solids. These materials do not have a long-range ordered structure like crystals, but instead, their atomic or molecular arrangements are disordered, similar to the structure of a liquid. One common example of such materials is glass.

2. A structure that is intermediate between solid and liquid is called

• A. metallic solid.
• B. polymeric solid.
• C. crystalline solid.
• D. amorphous solid.

Explanation: Here's an explanation: * D) Amorphous solid: An amorphous solid is considered an intermediate structure between a solid and a liquid because it lacks the long-range, repeating, ordered atomic structure characteristic of a crystalline solid. Unlike crystalline solids, amorphous solids do not have a distinct melting point; instead, they gradually soften over a range of temperatures, behaving somewhat like very viscous liquids. This lack of a definitive structure and gradual transition behavior makes them intermediate. Glass, plastics, and gels are common examples of amorphous solids.

3. In terms of structure, nylon is an example of

• A. glassy solids
• B. polymeric solids
• C. crystalline solids
• D. amorphous solids

Explanation: Nylon is classified as an amorphous solid because its molecular chains are arranged in a random or disordered manner, unlike the highly ordered structure of crystalline solids. This lack of long-range order gives amorphous solids unique properties. The other options are incorrect because nylon does not exhibit the characteristics of glassy, polymeric, or crystalline solids.

4. A solid containing irregular arrangement of molecules produces irregular fragments uponbreaking. This solid is calledI. amorphousII. crystallineIII. polymeric

• A. I only.
• B. II only.
• C. I and III.
• D. II and III.

Explanation: The correct answer is I only. Amorphous solids are characterized by an irregular arrangement of molecules, which causes them to break into irregular fragments. In contrast, crystalline solids have a regular, repeating pattern of molecules, leading to well-defined fragments upon breaking. Polymers can have both regular and irregular structures, but the question specifically refers to the irregular arrangement leading to irregular fragments, which is characteristic of amorphous solids.

5. A body which breaks down just after crossing the elastic limit is known as:

• A. Elastic
• B. Hard
• C. Ductile
• D. Brittle

Explanation: A body that breaks down immediately after crossing the elastic limit is known as brittle.

6. The given diagram shows a helical spring attached to a fixed surface. The value of spring constant is taken as 'k' 300 N/m and a 100 N weight is attached at the bottom.The extension in the spring will be

• A. 0.333 m
• B. 0.666 m
• C. 3 m
• D. 6 m

Explanation: The correct answer is 0.333 m. When a weight is attached to the spring, it exerts a force on the spring, causing it to extend. By applying Hooke's Law (F = kx), where F is the force, k is the spring constant, and x is the extension, we can calculate the extension in the spring to be 0.333 meters. Options B, C, and D are incorrect because they do not account for the force exerted by the weight of the object, leading to incorrect extension calculations.

7. The ratio between applied stress to the volumetric strain is called

• A. Bulk modulus.
• B. Shear modulus.
• C. Young's modulus.
• D. Modulus of plasticity.

Explanation: The correct concept for the ratio between applied stress and volumetric strain is the bulk modulus. However, the given correct option 'Young's modulus' is incorrect for the provided question. Young's modulus is specifically the ratio of stress to strain in the linear elasticity regime of a uniaxial deformation. The bulk modulus is indeed the correct term for volumetric stress-strain relationships. Therefore, the question seems to be incorrectly keyed.The other options are incorrect as follows:Shear modulus: Involves shear stress and shear strain, not volumetric strain.Modulus of plasticity: Is not a recognized term in standard material science terminology.Young's modulus: Refers to tensile stress and tensile strain, not volumetric changes.

8. The temperature below which the resistivity of a superconductor falls to zero is called

• A. Absolute temperature
• B. Kelvin temperature
• C. Limiting temperature
• D. Critical temperature

Explanation: The temperature below which the resistivity of a superconductor falls to zero is called the critical temperature or transition temperature, often denoted as Tc. Below this temperature, the material exhibits zero electrical resistance, becoming a superconductor. Above Tc the material behaves as a normal conductor.

9. Aluminium is a ........

• A. metal
• B. Photoconductor
• C. Non metal
• D. Semi conductor

Explanation: Here is the explanation of the correct optionAluminium is a metal

10. When N-type of semiconductor is heated :

• A. Number of electrons increases while that of holes decreases.
• B. Number of holes increases while that of electrons decreases
• C. Number of electrons and holes remains the same.
• D. Number of electrons and holes increases equally

Explanation: When an N-type semiconductor is heated, electrons gain energy and can move more freely, resulting in increased electrical conductivity. Additionally, heating causes the generation of electron-hole pairs, leading to an increase in both electrons and holes equally. Therefore, the correct option is that the number of electrons and holes increases equally. Other options are incorrect because they either ignore the creation of electron-hole pairs or incorrectly state the changes in charge carrier numbers.