Optical squares are simple sighting instruments used to set out right angles. They can be provided either with mirrors or with one or two prisms. Because of practical difficulties in using squares with mirrors, they have been replaced by squares with prisms: "prismatic squares".
Answer:
The maximum length of a surface flaw is 8.24 μm
8.24 μm
Explanation:
Given that:
The modulus of elasticity E = 69 GPa
The specific surface energy 
= 0.3 J/m²
The length of the surface flaw "a" = ??
From the theory of the brittle fracture;
Making a the subject of the formula; we have:
a = 8.24 × 10⁻⁶ m
a = 8.24 μm
Thus; the maximum length of a surface flaw is 8.24 μm
The correct answer is "immediately flood the area with water and clean the wound."
Further Explanation:
If someone is exposed to a potentially infectious material with a sharps item such a needle, they need to wash the area with clean water immediately. It must be a steady flow of water to get out any potential infectious material.
After flushing the injury with water, you will then wash the area or exposed skin with soap, if at all possible use a disinfectant on the area.
The person who was injured should seek medical assistance for tests to be sure that they have not been affected.
Learn more about infectious material at brainly.com/question/10928952
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