This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Miscellaneous Properties”.
1. The property of a material that produces an opposing magnetizing force, which removes the preceding magnetizing effect, is called as ___________
b) Coercive force
Explanation: Coercive force is that opposing magnetizing force which removes any preceding magnetizing effect. Permeability is the attribute which helps the magnetic field to be constructed. Hysteresis is the lag in magnetization due to variations in the magnetic field.
Explanation: Magnetic permeability is defined as the ratio of magnetic induction to the intensity of magnetic field (), whereas relative permeability is the ratio of permeability of medium to the permeability of free space (). Magnetization is defined by the equation , and ferromagnetism is the ratio of the intensity of magnetization to the intensity of magnetic field ().
3. What is the magnetic permeability of Iron?
a) 2.5 * 10-1
b) 2 * 105
c) 1.26 * 10-4
Explanation: The magnetic permeability of Iron (Fe) for 99.95% purity is 2.5 * 10-1 whereas its relative permeability is 2 * 105. Permeability and relative permeability values, decrease for lower purity levels of iron. The magnetic permeability of carbon steel is 1.26 * 10-4 whereas its relative permeability is 100.
4. The quantity or effectiveness of the energy emitted known as ____________
Explanation: Emissivity is defined as the effectiveness of emitting energy and thermal radiation. It is often also known as absorptivity. Luminance is the measure of luminous intensity. Refraction and reflection are the properties by which light changes direction, and change in a direction respectively.
5. What is the emissivity of aluminum foil?
Explanation: The emissivity of aluminum foil at room temperature is 0.03. The emissivity of polished silver and copper is 0.02 and 0.04 respectively, while that of concrete/brick is 0.9. Since emissivity is the ratio of the total emissive power of the body to the total emissive power of a perfectly black body, it does not have a unit.
6. The ability of a substance to neutralize the acidic nature of the material is known as ______
a) Corrosion resistance
b) Chemical composition
d) Chemical equilibrium
Explanation: Alkalinity is the ability of a substance which neutralizes the acidic nature of the material. Corrosion resistance is its ability to resist corrosion. Chemical equilibrium is the state in which the reactant and product do not vary anymore with time.
7. The ability of a metal which helps it to form a smooth cast is known as ______
Explanation: Castability is the ability of a metal or alloy by which a perfect cast is formed. The ease with which a material can be machined is known as machinability. The solderability is the ease with which a soldered joint can be prepared.
8. What is the machinability index of soft cast iron?
Explanation: Soft cast iron is a common construction material, which possesses a machinability index of 80. The machinability indexes of standard steel, ball bearing steel and cast copper are 100, 30, and 70 in that order.
9. Which of the following is an application of Tin solder 35?
a) Tinning and filling of seams
c) Secondary soldering
d) For materials which are difficult to solder
Explanation: Tin solder 35, which contains 35% of Sn and 65% of Pb, is used for plumbing work. Tin solder 20 is used for tinning and filling of seams, while Cd-Sn is used for secondary soldering with the composition of 50% Sn and 17% Cd. For difficultly soldered materials, Zn-Cd is used in 17 to 83 ratios.
10. Which property helps a material to absorb lubricants?
Explanation: Porosity is that property of a material which helps it to absorb lubricants, while density is the measure of the weight of unit volume. The solderability is the ease with which a soldered joint can be prepared. Absorptivity is an optical property of materials.
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