Exploding photographic film case

Introduction

Dry ice or coolant spray is put into film case and the lid of the film case is put on. When dry ice or coolant heats up the lid blows off.

Experiment gives an application of forces.

Pupils need to know about volume changes from liquid to solid to a gas.

Target age groups — GCSE or A level, 11 to 18

Equipment required

• A DrDAQ data logger running PicoScope oscilloscope software
• Force sensor (used Honeywell piezoelectric)
• Dry ice or coolant spray
• Photographic film cartridge

Experiment setup

• Connect the force sensor to the voltage and ground connections using DrDAQ’s screw terminals
• Place the film cartridge on the force sensor and step back. A piece of Blu Tack and a penny coin can be used to give a firm base for the sensor. Blu Tack can also be used to attach the sensor to the bench.

PicoScope settings

• Input: voltage
• Time settings: 1 ms/div.
• Trigger: single, volts, rising 10 mv, -2%

Carrying out the experiment

• Put coolant/dry ice into film case
• Push lid on hard
• Place film case onto the force sensor and step back sharply

Questions and discussion of results

1. What does the area under graph represent?
2. How would making the surface softer affect the graph?