Problem 2. The periodic array below denotes a hypothetical lattice in 2D. 1. Is this a Bravais lattice? Why or why not? (0.25 points) 2. Draw 3 different versions of unit cells. Of those 3 , make one a primitive unit cell. (0.25 points) 3. There is a special type of primitive unit cell that is called a 'Wigner-Seitz' cell (look it up online, or in text books). In words, describe how it is defined, and draw it for the lattice above. (0.25 points) 4. Why would it be useful to draw the primitive unit cell of a lattice as a Wigner-Seitz cell, rather than another random choice? ( 0.25 points. Hint : What geometric property of a lattice was described to be useful in guessing material properties during class?)