Free Physics of Solids MCQs with Answers

71. The ratio of volumetric strain to volumetric stress is called

• A. Compressibility
• B. Young's modulus
• C. Bulk modulus
• D. Plastic modulus

Explanation: Bulk modulus is a measure of the resistance of a material to uniform compression, defined as the ratio of the infinitesimal change in volume to the change in applied pressure.

72. The substance which undergoes plastic deformation until it breaks is:

• A. Ductile substance
• B. Brittle substance
• C. Plastic substance
• D. All of these

Explanation: Ductile substances are materials that can undergo significant plastic deformation before breaking. They can be drawn into wires or stretched into thin sheets without fracturing.

73. Choose the region of the spectrum which would be used to determine the structure of crystalline solid

• A. Visible
• B. Infrared
• C. X-rays
• D. Ultraviolet

Explanation: X-ray crystallography is widely used to determine the atomic and molecular structure of crystalline solids. X-rays have wavelengths on the order of atomic spacings, allowing them to diffract off the crystal lattice and produce detailed structural information.

74. If stress is doubled, then volume becomes?

• A. Double
• B. Half
• C. Four times
• D. None of these

Explanation: Stress applied is inversely proportional to the volume of the body so on doubling the stress volume will be reduced to half

75. Young modulus for the perfectly rigid body is

• A. 1
• B. 0
• C. infinity
• D. 40

Explanation: Young's modulus (E) is a measure of a material's stiffness. It is defined as the ratio of stress (σ) to strain (ε):E = σ/εA perfectly rigid body does not deform under any applied stress. This means that the strain is always zero, regardless of the stress. Therefore, the Young's modulus of a perfectly rigid body is infinite.

76. Aluminum is a

• A. Metal
• B. Non Metal
• C. Photo conductor
• D. Semiconductor

Explanation: Aluminum is a metal because it possesses all the characteristic properties of a metal. It is lustrous, malleable, ductile, and a good conductor of heat and electricity. Metals have a free electron structure which allows them to conduct electricity.

77. Negative strain indicates that

• A. Length is increased
• B. Length is decreased
• C. Length remains same
• D. None of these

Explanation: Strain is defined as the ratio of change in length to the original length.Strain = (Change in length)/ (Original length)If the change in length is negative, it means the length has decreased

78. In an extrinsic semi-conductor charge carriers are

• A. Holes
• B. electron
• C. No charge carriers
• D. Both a and b

Explanation: Extrinsic semiconductors are those whose conductivity is due to impurities. Extrinsic semiconductors are of two types: n-type and p-type. In n-type semiconductors, the majority charge carriers are electrons, and in p-type semiconductors, the majority charge carriers are holes

79. Which type of current passes through extrinsic semiconductors diode?

• A. Unidirectional
• B. Bidirectional
• C. Both a and b
• D. None of these

Explanation: Extrinsic semiconductors diodes are designed to allow current flow in only one direction. This is because of the p-n junction created within the diode. The p-type material has an excess of holes, while the n-type material has an excess of electrons. When a forward bias is applied, the holes from the p-type material move towards the n-type material, and the electrons from the n-type material move towards the p-type material. This creates a current flow. However, when a reverse bias is applied, the holes and electrons are pulled away from the junction, resulting in a very small reverse current. This unidirectional current flow is a key characteristic of diodes, making them suitable for applications such as rectifiers, which convert alternating current (AC) to direct current (DC).

80. Pascal is equal to:

• A. Newton meter squared
• B. Newton per meter squared
• C. Newton per meter cubed
• D. Newton meter cubed

Explanation: Pascal (Pa) is the SI unit of pressure. Pressure is defined as force per unit area.Force is measured in Newtons (N).Area is measured in square meters (m²).Therefore, Pascal can be expressed as:1 Pa = 1 N/m²