# 2.11: Questions

## Quick questions

You should be able to answer these questions without too much difficulty after studying this TLP. If not, then you should go through it again!

Which one of the following statements about the (241) and (241) planes is false?

 a They are perpendicular. b They are part of the same set of planes. c They are part of the same family of planes. d They are parallel.

A.

Does the  direction lie in the (301) plane?

 a Yes b No

B. no

When writing the index for a set of symmetrically related planes, which type of brackets should be used?

 a (Round) b {Curly} c d [Square]

B.

Which of the <110> type directions lie in the (112) plane?

 a  and  b  and  c  and  d  and 

D.

What is the common direction between the (132) and (133) planes?

 a  b  c  d 

B.

Which set of planes in a face centred cubic lattice, is close packed?

 a {110} b {100} c {111} d {222}

C.

## Open-ended questions

The following questions are not provided with answers, but intended to provide food for thought and points for further discussion with other students and teachers.

Practice sketching some lattice planes. Make sure you can draw the {100}, {110} and {111} type planes in a cubic system.

Draw the trace of all the (121) planes intersecting a block 2 × 2 × 2 block of orthorhombic (a ≠ b ≠ c, α = β = γ = 90°) unit cells.

Sketch the arrangement of the lattice points on a {111} type plane in a face centred cubic lattice. Do the same for a {110} type plane in a body centred cubic lattice. Compare your drawings. Why do you think the {110} type planes are often described as the "most close packed" planes in bcc?