Free Physics of Solids MCQs with Answers

301. Select the true statement about the amorphous solids:

• A. Amorphous substances have a sharp melting point
• B. Amorphous substances do not have a fixed melting point
• C. Amorphous substances have proper geometrical shapes
• D. The particles in amorphous substances are arranged in an orderly manner

Explanation: Amorphous solids, unlike crystalline solids, do not have a fixed melting point. This is because they lack the ordered structure that characterizes crystalline materials. Instead, they soften gradually over a range of temperatures. For example, glass softens before melting completely. Amorphous solids have a disordered atomic or molecular structure, which results in their unique properties such as isotropic behavior and lack of sharp melting points. Option B correctly identifies this characteristic, whereas the other options incorrectly attribute properties of crystalline solids to amorphous ones.

302. Choose the anisotropic behavior

• A. Coefficient of thermal expansion
• B. Lattice energy
• C. Viscosity
• D. Infrared spectroscopy

Explanation: Anisotropy is the property of a material which allows it to change or assume different properties in different directions so the correct option is A i.e coefficient of thermal expansion as there are 3 coefficients i.e for volume, area and linear expansion

303. Which of the following does not show anisotropy?

• A. Diamond
• B. Graphite
• C. Glass
• D. Rock salt

Explanation: Glass is an isotropic material, meaning its properties are the same in all directions. It lacks the ordered crystalline structure that leads to anisotropy in materials like diamond and graphite.Anisotropy refers to the property of a material exhibiting different physical properties along different axes.

304. The applied force that the solid can withstand without breaking is called:

• A. Stiffness of solids
• B. Strength of solid
• C. Ductility of solids
• D. Toughness of solid

Explanation: Strength measures how much stress can be applied to an element before it deforms permanently or fractures.

305. The applied force which the solid can withstand without breaking is called

• A. Stiffness of solids
• B. Strength of solid
• C. Ductility of solids
• D. Toughness of solid

Explanation: Strength measures how much stress can be applied to an element before it deforms permanently or fractures.

306. The substances which undergo deformation with a small force are called;

• A. Elastic substances
• B. Inelastic substances
• C. Diamagnetic substances
• D. Ductile substances

Explanation: Elastic substances are materials that undergo deformation when subjected to small forces, but they can return to their original shape and size once the force is removed.

307. The ratio of volumetric strain to volumetric stress called:

• A. compressibility
• B. young's modulus
• C. bulk's modulus
• D. shear's modulus

Explanation: Compressibility is the ratio of volumetric strain to volumetric stress. It is the inverse of bulk's modulus. Its SI unit is the pascal. Strain: A force tending to pull or stretch something to an extreme or damaging degree Stress is a quantity that describes the magnitude of the forces that cause deformation (strain).

308. The substance that undergoes plastic deformation until it breaks is:

• A. ductile substance
• B. brittle substance
• C. plastic substance
• D. all of these

Explanation: The substance which undergoes plastic deformation until it breaks is a DUCTILE SUBSTANCE. Therefore, option 'A' is correct.

309. The spring constant of a spring is k. If the spring is cut into two halves then the spring constant of one of the halves is:

• A. k + 2
• B. k/2
• C. 2k
• D. k

Explanation: According to Hooke's Law, the force exerted by a spring is given by F = -kx, where k is the spring constant and x is the displacement. The spring constant is a measure of the spring's stiffness. When a spring is cut into two equal halves, each half becomes stiffer because the same force is now applied over a shorter distance. Therefore, the spring constant of each half becomes twice the original, or 2k. The other options are incorrect because they do not accurately reflect this relationship. Option A incorrectly adds a constant, Option B incorrectly assumes the spring constant is halved, and Option D assumes the spring constant remains unchanged.

310. A spring obeying Book's law has an unstretched length of 50 mm and a spring contant of 400 Nm-01. What is the tension in the spring when its overall length is 70mm?

• A. 8.0N
• B. 28N
• C. 160N
• D. 400N

Explanation: According to Hooke's Law, the force F exerted by a spring is directly proportional to the displacement x from its equilibrium position, which can be expressed as F = kx.In this problem, the unstretched length of the spring is 50 mm. The stretched length is given as 70 mm, so the displacement x is 70 mm - 50 mm = 20 mm, which is 0.02 meters.The spring constant k is given as 400 N/m. Therefore, the tension in the spring is F = 400 N/m * 0.02 m = 8 N.Options B, C, and D are incorrect because they either miscalculate the displacement, misapply the spring constant, or misunderstand the relationship given by Hooke's Law.