Forensic Science and Physical Evidence Questions and Answers

Answer: B

IEC stands for the International Electrotechnical Commission.

ISO/IEC 17025:2017, the international standard for the competence of testing and calibration laboratories, is published jointly by the International Organization for Standardization (ISO) and the IEC. Forensic laboratories are accredited against it, in India by NABL.

The other expansions ('Eligibility Certification', 'Efficiency Commission', 'Efficiency Certification') are invented; the IEC is the body that sets standards for electrical and electronic technologies.

Answer: A

They are approaches for estimation of location of cellphones.

Time of Arrival measures how long a signal takes to travel between a phone and base stations; Time Difference of Arrival compares arrival times at several stations; and Enhanced Observed Time Difference, used in GSM networks, has the handset measure timing differences between base stations. Each gives distances from which the phone's position is calculated.

These are positioning techniques, not network protocols, and they have nothing to do with note-making or documenting a crime scene, though their results are used as digital evidence.

Answer: A

The fastest shutter speed is 1/2000 second.

Shutter speed is the time the shutter stays open, so the smaller the fraction of a second, the faster it is. 1/2000 s is shorter than 1/1500, 1/1000 and 1/500 s, and is used to freeze fast movement.

The trap is to read the larger denominator as a longer time; in fact 1/500 s is four times longer than 1/2000 s.

Answer: A

The Article is Article 24.

Article 24 of the Constitution provides that no child below the age of fourteen years shall be employed to work in any factory or mine or engaged in any other hazardous employment. It is one of the Fundamental Rights against exploitation.

Article 23 prohibits trafficking and forced labour, Article 22 gives protection against arrest and detention, and Article 21 protects life and personal liberty.

Answer: C

The Bank Identification Number is the first six numbers of the card.

The BIN, or Issuer Identification Number, has traditionally been the first six digits of a payment card number. The first digit shows the card network (4 for Visa, 5 for Mastercard), and the six digits together identify the issuing bank. The industry has been moving to eight-digit BINs, but six is the standard answer.

The first digit alone shows only the network, and the first three or four digits are not enough to identify the issuer.

Answer: A

The correct statement is that F1 will be higher in low vowels.

The first formant (F1) is linked to tongue height: the lower the tongue and the more open the mouth, the higher the F1. So low (open) vowels such as /a/ have a high F1, around 700 to 800 Hz, while high (close) vowels such as /i/ and /u/ have a low F1, around 300 Hz.

The other statements reverse this relation. Schwa, a mid vowel, has an F1 between the two extremes, higher than in high vowels, so the last option is also wrong.

Answer: A

An MFT record header starts with the identifier FILE.

In the NTFS file system, every entry in the Master File Table begins with the four-byte signature 'FILE' (hex 46 49 4C 45). Forensic tools use this signature to find and carve MFT records, even in unallocated space. A record marked as corrupted carries 'BAAD' instead.

'NULL', 'ARRAY' and 'CLUSTER' are not MFT signatures; a cluster is a unit of disk allocation, not a record identifier.

Answer: C

Automatic identification systems mostly use the Mel frequency cepstral coefficient.

In automatic speaker recognition (printed here as 'species identification'), speech is described by Mel frequency cepstral coefficients (MFCCs), computed on the Mel scale, which spaces frequencies the way the human ear perceives pitch. MFCCs summarise the shape of the vocal tract and are the standard features in such systems.

'Hertz', 'formant' and 'normal' frequency cepstral coefficients are not standard feature types; formants are measured separately in forensic phonetics.

Answer: A

The time is called the reaction time.

In accident reconstruction, reaction (or perception-reaction) time is the interval between a driver perceiving the need to stop and actually applying the brakes (printed here as 'break'). It is usually taken as about 0.75 to 1.5 seconds, during which the vehicle continues at full speed.

Braking time is the time from the brakes being applied until the vehicle stops. 'Friction time' is not a standard term, and 'response time' is less specific than reaction time.

Answer: A

The microscopic crime scene is a wound on a dead body.

Crime scenes are classified by size: the macroscopic scene is the large area, such as a room, a riverbed or a road, while microscopic scenes are the small areas that carry trace evidence, such as a wound, a bloodstain, a bullet hole or a body's clothing. A wound, with its gunshot residue, fibres or tool marks, is examined as its own small scene.

The room, the riverbed and the place of a hit-and-run are all macroscopic scenes.