Question 4 (a) Answer the following questions on scanning electron microscopy (SEM). (i) Which are the three useful signals detected? (ii) Name two contrast modes. (iii) What are the key aberrations? (iv) Name the technique for chemical characterization of the sample. (b) What are the characteristics of burst signals in acoustic emission testing? (c) Name FOUR Acoustic emission sources.

Question 4 (a) Answer the following questions on scanning electron microscopy (SEM). (i) Which are the three useful signals detected? (ii) Name two contrast modes. (iii) What are the key aberrations? (iv) Name the technique for chemical characterization of the sample. (b) What are the characteristics of burst signals in acoustic emission testing? (c) Name FOUR Acoustic emission sources.