I chose the clip “1.21 Gigawatts” from Back to the Future. In this clip, Marty accidentally takes a time machine in the past and confronts Doc’s past self for help. Marty shows Doc his future videos documenting the details of the time machine. After learning they need 1.21 gigawatts of energy to power the time machine, Doc believes that Marty has no way of getting back to the future as that amount of energy will be impossible to achieve without a bolt of lightning. However, Marty knows about a lightning strike that will happen soon, which gives Doc an idea and some newfound motivation.

There are two main diegetic sounds in this clip. The first diegetic sound is the TV clip, which is necessary for Doc to learn information about the time machine. The second sound is the dialogue between the characters, which help to move the movie forward. There are other various minor diegetic sounds in the clip, like the paper crumpling. Near the end of the clip, there is some nondiegetic music added.

The music begins as soon as Marty realizes that he knows when lightning will strike and thus has a way to get back to the future. Afterward, Doc has formulated an idea to send Marty back to the future. The music helps give a dramatic buildup to the scene, and it builds up to a final dramatic release that leaves the clip with optimistic expectation. To achieve this effect, the music starts off with only a single horn giving some steady low notes. Next, the music gradually crescendos and more instrument layers are added while doc is explaining his ideas. Finally, the instruments play one last loud, dramatic chord right before Doc shouts “back to the future.” The buildup of the music helps the clip to end with a triumphant feeling.