What factor increases the strain in a crystal?

• A. Higher temperature
• B. More dislocations in the crystal
• C. Larger crystal size
• D. Longer diffusion path

Answer: (B)

Strain in a crystal comes from distortions in the regular lattice caused by defects. Dislocations are line defects that distort the surrounding atomic arrangement, creating a local stress field and stored elastic energy. When there are more dislocations, there are more regions of distortion and their stress fields can interact, increasing the overall internal strain in the crystal. Temperature can relieve strain because higher atomic mobility allows rearrangements, glide, and annihilation of defects, which can reduce distortion. Crystal size by itself doesn’t create more lattice distortion, and a longer diffusion path changes how quickly atoms move rather than increasing the static strain stored in the lattice.