Materials Flashcards
Why is PVC plastic used to make children’s buckets and spades?
High resistance to water damage
Cheap
Low density
What are the benefits of nanoparticles in sun cream?
Rubs to a clear film; doesn’t leave a white residue
Better coverage
More protection
What are the risks of using nanoparticles in sun cream?
Nanoparticles may be harmful if they’re able to enter human cells
May be issues with safe disposal of nanoparticles
What is a smart material, and what does it do?
A material †hat changes how it behaves as a result of its surrounding.
Thermochractic materials - change colour due to change in temperature, e.g. feeding spoons
Photocromatic materials - change colour expending on exposure to light,e.g. (sun)glasses
1 nano metre =
1 x 10-9 m
What are collected at crime scenes?
Fingerprints DNA Blood Hair Clothing fibres Explosives Drugs Digital evidence (photos)
What do forensic scientists collect at crime scenes?
Clothing fibres
Soil
Vegetation
Glass fragments
What type of fingerprints are there?
Arch
Loop
Whorl
Composite
What do we use to find fingerprints on a white surface?
Carbon black powder
What do we use to find a fingerprint on a black or mirrored surface?
Aluminium dust or powder
What is used if fingerprints are found on a surface that can’t be dusted by powder?
Superglue vapour
Iodine fumes
What will iodine fumes show fingerprints up on?
Paper
Clothing
Skin
What is the process for collecting fingerprints?
- Excess dust is brushed off
- Sticky tape pressed over print
- Print is transferred to tape and placed onto card
How are fingerprints used for modern policing?
All fingerprints will be scanned into a computer and compared with a fingerprint database to identify the suspect
