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MCQ quiz on Material science multiple choice questions and answers on material science MCQ questions quiz on material science objectives questions with answer test pdf. trailer You can google or memorize the answer quite easily, but in a test you might get extra points for deriving the result yourself. The expanded version would look like this: Additionally, atomic packing factor uses the hard sphere model. The slip direction lies on the slip plane. To visualize this, imagine that you joined many unit cells together. The following section consists of Chemistry Multiple Choice questions on Atomic Structure For competitions and exams. It is almost unmachinable (C) Is produced by annealing process. If you projected the atom into one of those planes, it would be exactly in the middle of 3 atoms. MCQ 5 MCQ 6 MCQ 7 MCQ 8 MCQ 9 >> 1. Now we can plug into our first pythagorean theorem. Miller indices for triangular plane in cubic crystal. In this case, the body diagonal is . b. (B) Is also known as chilled cast iron and is obtained by cooling rapidly. By geometry, the length of the diagonal is a*√3. MODULE NO 2 – MCQ on Crystallography What is the atomic packing factor of BCC structure? Volume of the atoms divided by volume of the unit cell. 0000001675 00000 n So each of the 8 atoms contributes ⅛ of its total volume. Lattice parameter is the length between 2 touching atoms (so, twice the radius). space lattice is (A) 2 (B) 4 (C) 6 (D) 8. The face diagonal, therefore, has a length of . Body centered cubic structure has an atomic packing factor equal to. coordination number. Let’s draw a line between the center of the triangle and one of its corners. The line needs to be along the crystal “cell.”. Select the correct option to test your skills on Atomic Structure. Lattice parameter is the height of the unit cell. In crystallography, atomic packing factor (APF), packing efficiency, or packing fraction is the fraction of volume in a crystal structure that is occupied by constituent particles. Since that entire atom is inside the cell, it fully contributes its volume. Atoms are locate at eight corners and a single atom at the centre of cube. Imagine you had to pack spheres into a box. Coordination number in simple cubic crystal structure (a) 1 (b) 2 (c) 3 (d) 4 10. As we’ve seen several times already, there will be 8 atoms on each corner, each contributing ⅛ of its total volume to the unit cell. Read Online Material Science Mcq GATE, IES, PSU, NET/SET/JRF, UPSC and %PDF-1.4 %���� 0000005613 00000 n (a)BCC (b) FCC (c) SCC (d) HCP. MCQ quiz on Material science multiple choice questions and answers on material science MCQ questions quiz on material science objectives questions with answer test pdf. In metals there is usually only one atom, but in a ceramic, suppose there are 3 kinds of atoms: , , and . Again, the 2nd plane can be arranged as close-packed. 0000051222 00000 n 17.What is the atomic packing factor of BCC structure? In an FCC crystal, any face diagonal is the close-packed direction. This is a rhombohedral cell. 16. As long as the line you draw is a valid representation of the overall crystal symmetry, any line will work! Now that we have and , we can calculate the volume of the hexagonal unit cell. 0000007747 00000 n 8. Metallurgical Engineering Topic wise MCQ / Crystal Systems. Following is the list of multiple choice questions in this brand new series: MCQ in Electricity and Magnetism Fundamentals. Total = 2 atoms per unit cell. It is a dimensionless quantity and always less than unity. In crystallography, atomic packing factor (APF), packing efficiency, or packing fraction is the fraction of volume in a crystal structure that is occupied by constituent particles. Of course, you can’t just draw any random line. 183. inversely proportional to . 0000001064 00000 n The area of the hexagon is just 6 equilateral triangles. Mechanical Behavior of Metals Crystal Structure - Mechanical Engineering (MCQ) questions and answers. a) 6 b) 8 c) 10 d) 12; What is the atomic radius of a BCC crystal structure? x�b```f``e`e``Sa`@ �(���_���L���SHXY����Et����2�eP�,dc���!���i�v�>��%�W��0�a���Ȑ������H31��팬�!|�Y% cl 10. If you’re a big-time nerd and you already know how to calculate the centroid of an equilateral triangle, keep reading. © 2021 Copyright Materials Science & Engineering Student, link to Hexagonal Close-Packed (HCP) Unit Cell, Body-Centered Cubic (BCC) Lattice Length and APF, Face-Centered Cubic (FCC) Lattice Length and APF, Hexagonal Close-Packed (HCP) Structure and APF. Engineering Materials MCQ question is the important chapter for a Mechanical Engineering and GATE students. Since we’re in 1-dimension, “space” means “length.” We can say that 1-dimensional packing is a linear density. A family of directions is represented by 12. Examples: Some examples of metals that have the BCC structure include Lithium (Li), … Coordination number in simple cubic crystal structure (a) 1 (b) 2 (c) 3 (d) 4 10. Remember, we want to find the space taken by atoms compared to the total space. Madelung constant . These two arrangements have the same packing. Now we can make another triangle, between , , and . a) 0.54 b) 0.68 c) 0.74 d) 0.96 Answer: b Explanation: The density of packing in a crystal is determined using the atomic packing factor (APF). The body-centered cubic crystal structure contains eight atoms on each corner of the cube and one atom in the center. Alright, now we’re getting to the less-common crystal structures. Simply find a crystallographically repeating area (the unit cell will always work) and divide that area by the area covered by the circles. c. The slip direction is perpendicular to the slip plane. 0000002771 00000 n Determining the packing factor works exactly the same way, however. space lattice. As in the simple cubic example, there are 8 corner atoms. Material Science MCQ Questions and Answers Quiz 1. 0000009089 00000 n Which of the following crystal systems is the most unsymmetric of all ... molecules or ions that a central atom or ion holds its neighbours in a complex or crystal is called. Since this is the smallest unit cell possible, we call this the HCP primitive unit cell. Because the angles of an equilateral triangle are all 60°, the angle between and is 30°. See, if the atoms are not “close-packed,” the unit cell will need to have more space. Let’s get the unit cell in terms of the atomic radius! Remember, APF is just the volume of the atoms within the unit cell, divided by the total volume of the unit cell. . 0.68 c. 0.52 d. None of the above. Science multiple choice questions and answers with explanation. Crystal Systems 13. 0000051478 00000 n We call this unit cell “hexagonal close-packed” because it looks like hexagonal planes. Now, we have 2 variables: (radius of atom) and (side length of cube). If you look at the central atom in the primitive cell, you can see that it has a distance between the atoms in the plane above and in the plane below. Dividing the volume of 4 atoms by the volume of the cube gives us the atomic packing factor for a face-centered cubic crystal: The HCP crystal structure is not cubic. a. Therefore, the length of each side o… This is the hexagonal close-packed lattice! 0000001534 00000 n Additionally, there is an atom in the middle of the cell. Now that we know the volume of the HCP unit cell, we can calculate it’s APF! 0000007008 00000 n You can use any variable you like for this length; I will choose . The volume of the atoms, and the volume of the unit cell. Atomic packing factor is (a) Distance between two adjacent atoms (b) Projected area fraction of atoms on a plane (c) Volume fraction of atoms in cell (d) None 9. Now we need to find the height of the triangle. For any particular direction, you need to draw a line and determine what percent of the line is covered by a circle. At first glance, it looks like there are 8 atoms: on on each corner of the cell. Material Science MCQ . 0 msestudent is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. This position is the center of the equilateral triangle. 0000001993 00000 n Atomic packing factor (APF) B. Ionic Packing Ratio (IPR) C. Atomic compacting factor (ACF) D. Ionic compacting ratio (ICR) View Answer: Answer: Option A. Atomic Packing Factor (APF) APF = Volume of atoms in unit cell* Volume of unit cell *assume hard spheres • APF for a simple cubic structure = 0.52 APF = a3 4 3 1 π (0.5a)3 atoms unit cell atom volume unit cell volume close-packed directions a R=0.5a contains 8 x 1/8 = 1 atom/unit cell MCQ No - 1. You’ve learned how to calculate the lattice parameters and atomic packing fraction for simple cubic (SC), body-centered cubic (BCC), face-centered cubic (FCC), and hexagonal close-packed (HCP) crystal systems. Coordination number of BCC crystal structure is 8, and its atomic packing factor is 0.68. If we divide the volume of 2 atoms by the volume of the unit cell (), we find that the atomic packing factor for a body-centered cubic crystal is: This should be familiar by now. Simply take the length of the line covered by circles, and divide by the total length of the line. Can you explain this answer? The hard part is behind us. We can call this . Each corner atom contributes ⅛ of its volume to the unit cell, so that’s equal to 1 whole atom. The other leg will be the face diagonal. Assuming the atoms are hard spheres with radius in a cubic unit cell with lattice parameter . Page-3 section-3 Learn Engineering Materials MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Curie-Weiss Law . The Hexagonal Close-Packed (HCP) crystal structure is one of the most common ways for atoms to arrange themselves in metals. In total, there is 1 full atom per unit cell. There are two atoms per unit cell of a BCC structure. For cubic crystals, A.P. Now, let’s find . 0000008445 00000 n In total, there are 2 atoms in the BCC unit cell. MCQs of Crystal Geometry and Crystal Imperfection. It is a dimensionless quantity and always less than unity. The packing factor of FCC is 0.74: Number of Spheres in a Unit Cell: A unit cell of BCC has a net total of 2 spheres.

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