Which of the following options is INCORRECT?
Try it first: pick an option, then read the explanation.
Correct answer: C. −(Longitudinal strain ÷ Lateral strain) = Poisson's ratio
Asked in SSC JE 15/11/2022 (Shift 3)
Detailed Explanation
Pull a bar: it gets longer (longitudinal strain) and thinner (lateral strain). Poisson's ratio compares the two.
\[ \mu = -\frac{\varepsilon_{lateral}}{\varepsilon_{longitudinal}} \]
Why “−(Longitudinal strain ÷ Lateral strain) = Poisson's ratio” Is Correct
Statement (c) inverts the ratio, so it is the incorrect one. Since μ ≤ 0.5, the lateral strain is generally smaller than the longitudinal strain — statement (d) is true.
Why the Other Options Are Wrong
- A. Lateral strain can be measured along the transverse direction: True: lateral strain is measured across the member.
- B. Longitudinal strain acts along the longest dimension: True: the longitudinal (axial) strain is along the length.
- D. Lateral strain is generally less than longitudinal strain: True: since μ < 1 (≤ 0.5), lateral strain is smaller.
Key Point
μ = lateral ÷ longitudinal (not the reverse).
Key Concepts for Students
- The minus sign makes μ positive (lateral strain is opposite in sign).
- m = 1/μ is sometimes called Poisson's number.
- Lateral strain = −μσ/E.
Practice more: this is question 6 in Stress and Strain MCQs – Part 1. Try the whole set and check every answer instantly.