Forensic Physics

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

ExplanationTools 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

ExplanationAll 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

ExplanationDifferent 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

ExplanationThese 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

ExplanationPhotography 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

ExplanationSilicone 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

ExplanationTool 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

ExplanationCrime 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

ExplanationTool 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

ExplanationThese 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

ExplanationThe 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

ExplanationIn 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

ExplanationElectrolysis 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

ExplanationBlack 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

ExplanationFry’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.

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