A 150 mm long cylinderical rod having a diameter of 100 mm contains six microvoids which are situated at radial distances of 5 mm, 8 mm, 12 mm. 20 mm, 30 mm, 36 mm respectively, on a given r-z plane. Along the length (z-direction) of the rod, the voids are spaced uniformly. The specimen is to be tested by an ultrasonic cylinderical probe, 7.5 mm in diameter: The maximum number of flows, that can be detected in a single measurement by placing the probe at one end of the rod (flat surface) is

Fatigue life is expected to increase by

A. increasing the size of the sample

B. smooth polishing of the surface of the sample

C. having compressive residual stresses at the surface

D. having tensile residual stresses at the surface

Which of the following is a function of a developer

A. Providing a contrasting background for visible dye indications

B. Making the penetrant water washable

C. Penetrating into discontinuities open to the surface

D. Dissolve organic soils on the test piece surface

With an increase in temperature, hardness of material . . . . . . . . and ductility . . . . . . . .

A. Increases, increases

B. Increases, decreases

C. Decreases, increases

D. Decreases, decreases

A brale indentor used in Rockwell hardness test has the following geometry and material.

A. Square based diamond pyramid with 136° included angle

B. Conical shape steel with 120° apex angle

C. Conical shaped diamond with 120° apex angle

D. 10 mm diameter hardened steel ball