- The following 10 observations were recorded when measuring a voltage.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| 41.7 | 42 | 41.8 | 42 | 42.1 | 41.9 | 42.5 | 42 | 41.9 | 41.8 |
Find.
- Mean
- Standard deviation,
- Probable error of one reading
2. What is LVDT ? Explain its working with necessary diagrams and characteristics. What are its advantage and uses ?
3. Define longitudinal strain and lateral (transverse) strain. Explain their physical meaning and give the mathematical expressions for each.
4. Define Poisson’s ratio. Derive the relation between Poisson’s ratio and the longitudinal and lateral strains for a prismatic member subjected to uniaxial tension.
5. A metallic strain gauge of resistance R and resistivity is bonded along the axis of a bar undergoing a small axial (longitudinal) strain e. Starting from
,derive an expression for the fractional change in resistance in terms of e, Poisson’s ratio, and the fractional change in resistivity
6. Using the result from (5), define the gauge factor GF of the strain gauge and show that for small strains:
7. Calculate the gauge factor of a strain gauge if a 1.5mm diameter conductor that is 24mm long changes length by 1mm and diameter by 0.02 mm under a compression force.
8. How does a Piezo-electric transducer work ? What are the common materials used for it ?
Derive an expression for its
- voltage and
- charge sensitivities. Draw the equivalent circuit for this transducer.