With reference to electric arc welding:

(a) Draw a labeled sectional sketch of a satisfactory butt weld. (6)

(b) Briefly define the following defects that may occur and how they may have been (6)

(i) Under cut

(ii) Splatter

(iii) Inclusion

(iv) Blow hole

(v) Incomplete root penetration

(vi) Lack of fusion

(c) Why is alternating current generally more popular then direct current for metal arc welding? (4)