Forensic
Physics Quiz Crafted by-
Dr. Rajeev Kumar
Associate Professor
Division Chair (Division of
Physical Science)
Department of Forensic
Science
School of Basic &
Applied Sciences, Galgotias University
Introduction to Forensic Physics
Forensic Physics is the
application of physics for the purpose of civil and criminal law. It
involves the examination of paint, glass, soil, fibres, tool marks, etc.T ool
marks are made when harder surface comes in contact with a softer surface. They
are encountered at burglary crime scenes which involves forcible entry. Toolmark
identification aims to identify tools as the source of marks on crime scenes.
Tools leave unique marks on surfaces such as firearms identification which
deals with marks left behind by bullets, cartridge cases and shotshell
components. Comparison microscope is used for the purpose of comparison of
evidence tool marks found at crime scenes with test tool marks as comparison
microscope allows side by side comparison.
Here is the List of Questions with Answers along with explanation
Ques 1. Following
features are analysed for tool marks identification?
a) Dimensions
b) Patterns
c) Defects
d) All
Answer. (d)
All
Explanation: Tools have class characteristics which are formed
due to their distinctively designed features such as rifling impression on
bullets showing the number, width and direction of twist of lands and grooves,
dimensions and patterns. Tool marks also have individual characteristics, these
are the irregularities which are formed during manufacturing processes or with
successive use, corrosion or damage. During the analyses of tool marks these
characteristics are analysed for the purpose of identification.
Ques 2. Which
of the following are examples of tool that criminals may use?
I. Screwdrivers
II. Crowbars
III. Bolt cutters
a) I, II, III
b) I
c) I, II
d) I, III
Answer. (a)
I, II, III
Explanation: All these tools can be utilized by a perpetrator
depending on the type of situation and need of the criminal.
Ques 3. Following
can be used for casting of tool marks
a) Plaster of Paris
b) Dental casting
c) Cellulose acetate
d) All
Answer. (d)
All
Explanation: Different materials are used for the casting of tool
marks depending on the location and dimension of the tool mark like cream
silicone is used for vertical surface. Plaster of Paris is used when the
impression id of large size. Dental casting is used for lifting fine details of
a tool mark. Cellulose acetate material is used for lifting the tool marks from
stone, concrete, wood, etc.
Ques 4. Following
are the types of tool marks
a) Cut
b) Impression
c) Gouge
d) All
Answer. (d)
All
Explanation: These are all types of tool marks which are formed
along the edge as a surface is cut, when a tool’s harder surface comes in
contact with the softer surface or when two surfaces slide across one another.
Ques 5. Following
methods can be used for analysis of tool marks
a) Photography
b) Tracing
c) Casting
d) All
Answer. (d)
All
Explanation: Photography of the tool marks should be done using a
scale, tracing should be done using a tracing paper as it helps in comparing
the class characteristics and cast should also be made for comparing and
analysing the individual characteristics.
Ques 6. Which
of the following is the best choice to create a cast of a tool mark?
a) Silicone
b) Clay
c) Play duh
d) Papier-Mache
Answer. (a)
Silicone
Explanation: Silicone based casting material can be used to capture
the surface features of a variety of impressions encountered at the crime
scenes. The resulting casts preserve the fine details of the various marks and
can be used by the firearm section for comparative examinations.
Ques 7. Cellulose
acetate casting is done for tool marks present in
a) Stone
b) Wood
c) None
d) Both
Answer. (d)
Both
Explanation: Tool marks from stone, wood, concrete, etc. are
lifted using cellulose acetate material which is made by dissolving cellulose
acetate in acetone making a 1/16-inch layer. The cast made using this material
should be photographed with a scale immediately as the layer is likely to
shrink after sometime.
Ques 8. The
comparison of test and scene tool marks is usually performed using:
a) A scanning electron microscope
b) A comparison macroscope
c) A Raman microscope
d) A comparison microscope
Answer. (d)
A comparison microscope
Explanation: Crime scene tool marks and test tool marks are
compared using a comparison microscope as it provides side by side comparison.
Ques 9. Tool
marks are most often encountered at which crime scene
a) Arson
b) Sexual assault
c) Burglary
d) Homicide
Answer. (c)
Burglary
Explanation: Tool marks are mostly encountered at burglary crime
scenes which involves a perpetrator to break in.
Ques 10. In
the examination of tool mark impressions, individuality of a tool can be
ascertained by:
a) Patterns of grooves and lands
resulting from the machining process
b) Patterns of hills and valleys as
minute imperfections
c) Patterns of striations created by
the manufacturer to trademark the tool
d) All
Answer. (d)
All
Explanation: These all are the individual characteristics of
tools, that is, these characteristics are unique or individual to tools as they
are formed during the manufacturing process. It is highly that two tools will
have same kind of imperfections so the presence of these minute imperfections
imparts individuality to each tool.
Ques 11. What
is the primary consideration in collecting impressions at a crime scene?
a) The preservation of the impression
or its reproduction for later use
b) Maintaining the chain of evidence
c) The obliteration of the impressions
based on weather conditions
d) Its admissibility in a courtroom
Answer. (a)
The preservation of the impression or its reproduction for later use
Explanation: The impressions are collected at a crime scene for
the preservation of the impression for later use as it will help in comparing
the crime scene tool mark with the test tool mark and also will serve as a
permanent record of the class and individual characteristics.
Ques 12. Following
are the methods for applying serial number
a) Die stamping
b) Rolling
c) Hot stamping
d) All
Answer. (d)
All
Explanation: In die stamping, an inverse positive of the character
to be stamped is created and then applied to the substrate under sudden
pressure. Rolling method is similar to die stamping method, where the
characters to be stamped are applied to the substrate with a slower and a
steadier pressure. Hot stamping is used in case of polymer substrates which are
resistant to cold stamping methods. This method is used to produce an impressed
character by heating a die prior to stamping.
Ques 13. Select
the method used for removing the rusting from the surface
a) Electrolytic method
b) Magnetic particle method
c) Laser-etched method
d) Ultrasonic cavitation method
Answer. (a)
Electrolytic method
Explanation: Electrolysis is used for metal restoration. It is a
method of separating bonded elements and compounds by passing current through
them. It is a better method than other rust removing methods such as sand
blasting, etc. as it is a non-destructive technique which does not removes good
metal along with the rust like other methods. The equipment required for
performing this method includes a plastic container, washing soda
(electrolyte), steel plates, and a battery source.
Ques 14. Sand
paper is also known as
a) Amery paper
b) Emery paper
c) Emeri paper
d) Enery paper
Answer. (b)
Emery paper
Explanation: Black sandpaper is commonly known as emery cloth,
which is used to smooth metal and removing rust.
Ques 15. Identify
the chemical method used on iron surface for restoration
a) Hume- Rothery reagent
b) Hatcher's reagent
c) Villela's reagent
d) Fry’s reagent
Answer. (d)
Fry’s reagent
Explanation: Fry’s reagent is a popular metallographic etchant for micro-etching. It
is a mixture of 40ml hydrochloric acid, 5g copper (II) chloride, 25ml ethanol
and 30ml water. It is utilized by forensic scientists or metallographers for
etching away ferrous metals including cast iron. It is most commonly used for
recovery of stamped serial number on cast iron or steel engine or firearm
parts.