In a Mohr's circle drawn on the σ–τ plane (σ = normal stress, τ = shear stress), the vertical diameter represents:
Try it first: pick an option, then read the explanation.
Correct answer: A. maximum shear stress
Asked in SSC JE 2013
Detailed Explanation
In Mohr's circle the horizontal diameter lies on the σ-axis and its ends are the principal stresses. The vertical diameter is perpendicular to it, through the centre.
Why “maximum shear stress” Is Correct
The top and bottom of the circle — the ends of the vertical diameter — have the largest possible τ, equal to the radius. So the vertical diameter represents the maximum shear stress (each half equals τmax; the full diameter equals σ₁ − σ₂).
Why the Other Options Are Wrong
- B. maximum normal stress: Maximum normal stress (σ₁) is the right end of the horizontal diameter.
- C. principal stress: Principal stresses are the ends of the horizontal diameter.
- D. minimum normal stress: Minimum normal stress (σ₂) is the left end of the horizontal diameter.
Key Point
Mohr's circle: horizontal diameter → principal stresses; vertical diameter → maximum shear (radius = τmax).
Key Concepts for Students
- Centre = (σ₁ + σ₂)/2 = normal stress on max-shear planes.
- Radius = √(((σx − σy)/2)² + τxy²).
- Angles on the circle are twice the real angles.
Practice more: this is question 18 in Principal Stress and Principal Planes MCQs – Part 2. Try the whole set and check every answer instantly.