Multiple Choice Question (MCQ)
Question: Which grade of file is used for heavy reduction of material?
A.
Smooth file
B.
Bastard file
C.
Second cut file
D.
Dead smooth file
Correct Answer: Bastard file
Explanation
The ratio of ultimate stress to the working stress is known as factor of safety. Its value is more than one.
Factor of Safety = Ultimate Stress/Working Stress
Working Stress = Ultimate Stress/Factor of Safety
Working Stress = 35/5 = 7 kg/mm2