In the music sequence whenever the shark is near or attacking it has its own theme tune which is made to build tension because when you hear that music you know it's the shark and that something is obviously going to happen although at some parts of the movie it does trick you by playing the music but nothing really exciting happens. Two other examples of music or silence is used to scare the audience to build tension is when the radio is playing on the beach then after the attack its silent and when all the characters at the beginning are sat round a fire and music is playing cheerfully which contrasts on what we all know is about to happen.
The second attack is when all the children are playing on the sea whilst there parents watch, sunbathing, on the beach and Brody is doing his job sat looking out for anything suspicious because of the previous attack. The shark then attacks the young boy. The camera angles build up tension because it goes beneath the water and makes it seem like it's from the sharks' point of view and when it was attacking it went from a distance so you could see all the people's faces and just how exactly he was attacked.
The director builds up fear for the shark by making the music seem sly and dangerous sounding and making it seem like the kind of music you would expect from a murder film. He also builds tension by showing all the attacks in detail and comes quite at a distance so you can see just what actually happens to the victims as if you were watching from the beach. And also he shows the fear of Brody's, the victims and the people watching reactions and showing their fear.
The first two attacks being...