A $10-$mm thick steel block $($with Modulus of elasticity $E=210$GPa, shear modulus $G=80$GPa, and mass density $=7800k\frac{g}{m^3})$ has one internal large crack at a depth of $2$ mm and a region of porosity, as shown below. Considering a pulse$-$echo test with an L$-$wave transducer, sketch the ultrasonic C$-$scan results for the:

$($a$)$ Time$-$Of$-$Flight $($TOF$)$ feature $($indicate exact values$).$

$($b$)$ Amplitude feature $($indicate only relative values$).$

zlongleftarrow

TIME OF FLIGHT C$-$SCAN

$($indicate exact values$)$

AMPLITUDE C$-$SCAN $($indicate relative values$)$