Free Physics of Solids MCQs with Answers

281. Dark plastic handlers often used on kitchen utensils because:

• A. The black material is good in radiation.
• B. The plastic is good insulator.
• C. The plastic is a good conductor.
• D. The plastic soften gradually with excessive heat.

Explanation: Cooking pots are provided with wooden or plastic handles because they are bad conductors of heat. This prevents the heat from the pan to transfer to our hands.

282. Ferromagnetic means:

• A. It is attracted by magnet
• B. It is iron-like in nature
• C. It can be magnetized
• D. It is an alkali metal

Explanation: The explanation for this question will be added soon.

283. The electrical conductivity of metal sometimes decreases with the?

• A. Increase in pressure
• B. Increase in temperature
• C. Decrease in temperature
• D. Decrease in pressure

Explanation: The electrical conductivity of metals decreases with an increase in temperature as with the increase in temperature, the positive metal ions also begin to oscillate and the motion hinders the free movement of mobile electrons between the positive ions.This hindrance decreases the electrical conductivity.

284. Which one of them can conduct electricity in solid state?

• A. Diamond
• B. Graphite
• C. Nail
• D. Iodine

Explanation: Graphite, C(s) can conduct electricity in a solid state. Graphite is a network solid and conducts electricity as it has delocalized molecular orbitals in which delocalized electrons are free to move. Hence, option B is correct.

285. The dimension of Young's Modulus is:

• A. M2L-1T2
• B. ML-1T-1
• C. ML-1T-2
• D. ML-2T-2

Explanation: Young's modulus is the slope of the initial section of the curve (i.e. m in y = mx + b). When a material reaches a certain stress, the material will begin to deform. It is up to a point where the structure of the material is stretching and not deforming. Unit of Young's Modulus =N/m2=kgm/s2m2=ms2kg=ML−1T−2.

286. Volume stress divided by volume strain equal to:

• A. Young's modulus
• B. Bulk modulus
• C. Shear modulus
• D. Hyper modulus

Explanation: Bulk modulus is the ratio or hydrostatic stress to the volumetric strain. Within the elastic range is called bulk modulus. It is denoted by K or B. Sometimes referred to as the incompressibility, the bulk modulus is a measure of the ability of a substance to withstand changes in volume when under compression on all sides. It is equal to the quotient of the applied pressure divided by the relative deformation.

287. Which of the following is the most ductile?

• A. Glass
• B. Copper
• C. Cast iron
• D. High carbon steel

Explanation: Ductility is the property of being drawn into wires, it is a permanent strain tension test.Copper can be drawn into very thin wires as it is a metal; its atoms have the ability to roll over each other into new positions without breaking the metallic bond.While cast iron is brittle and will break due to its weak tensile strength means that it will fracture before it bends or distorts.In case of high carbon steel, the carbon atoms are much smaller than iron atoms and as more carbon is put into a lattice or iron atoms, it becomes harder for the iron atoms to slide easily past each other because of the carbon, and the steel becomes much more brittle and less ductile.For glass, the molecular structure is made up of tetrahedral crystals which do not have large-area orderly crystalline structure therefore they rupture under stress.Hence copper is the most ductile.

288. The wire made of copper belongs to which specific kind of material?

• A. Ductile material
• B. Tough material
• C. Brittle material
• D. Deformed material

Explanation: Ductility is the ability of a material to be drawn or plastically deformed without fracture. It is therefore an indication of how 'soft' or malleable the material is.Hence, Copper is a versatile material as it can be drawn into sheets.

289. A wire of length 2m is attached with mass of 5kg vertically, tensile strain of wire is 0.3 x 10^-3, the extension in wire is:

• A. 1.5mm
• B. 2mm
• C. 0.15mm
• D. 0.6mm

Explanation: Strain is nothing but ratio of change in length to original length i.e Δl/L. We are asked to calculate extension meaning increase in length i.e Δl. strain= Δl/L Δl =strain x L =0.3x10-³ x 2 =0.6x10-³ =0.6mm ANS

290. The area under the extension-load graph Of an elastic material whose elastic limit has not been exceeded gives its:

• A. Stress
• B. Strain energy
• C. Strain
• D. Young modulus

Explanation: Strain energy is the energy stored by an object undergoing deformation. Area under the extension-load graph represents work done to cause the deformation. An object which has not reached its elastic limit, the work done during stretching is recovered when it is unloaded.