Big Explosion

This is a photo of a large explosion. The exposure is much improved. Still visible are the scratches on the Plexiglas. Also, the picture gave us an important piece of information. You can see the string at the times of the two flashes in two different positions, but the pendulum itself hadn't moved. This told us that our delay between flashes was long enough, but that our pendulum was too heavy to move. We therefore replaced our lead pendulum with a lighter one.