Answer / ali azam

Two main reasons:
1. Most of the signals of our interest are of low
frequency(information signals). But low frequency signals
are not transmissible so they have to be carried by high
frequency signals!
This is due to 2 reasons:
a)low frequency means longer antenna
b]low frequency signals are not powerful enough to be
transmitted at longer distances
To carry low frequency signals(information signal) by high
frequency carrier signals modulation must be done!!

2. For sending and receiving multiple signals at the same
time u need to send the signals at different frequency(other
ways they would interfere) which can only be done by
modulating them with different high frequency signals!

Answer / antony rebello.s

modulation is necessary in communication bcoz to reach the
destination the signal want some power to reach there.so
modulation is used 2 add an extra energy 2 signal 2 reach
destination........

Answer / abdul sattar memon

Modulation is required in communicatioj b/c the baseband transmission haa many limitations which can be overcome using modulation. Modulation is required in the reduction in the height of antenna.
It avoids mixing of signals.
Modulation icrease the range of communication

Answer / jamiyu m. jimah

For transmission of messages over long distances in the radio channel, there are two alternatives. The first is that either the signal (i.e. modulating signal) itself is transmitted or to use an unmodulated carrier

Answer / sai keerthana

increases the range of communication i.e.,low frequency can be increased to high frequency.we can overcome the equipment limitations.And wide band signal will be converted into narrow band signal.

Answer / marvelous ajumuka

modulation is used for frequency assignment i.e it allows several radio and television stations to broadcast simultaneously at different carrier frequency with the same transmission medium else there would be interference in signal.

DIRECTIONS (Q1-10).EACH QUESTION HAS TO BE ANSWERED FROM GIVEN PASSAGE. READING COMPREHENSION (PASSAGE) On 26th NOVEMBER, the airport police caught a youth Sravan kumar tried to smuggle 98 dried bear gall ladders out of the country. They looked like shriveled black mangoes, and no one but the expert could say that the weird looking things came from an animal. Even experts faltered in identifying the species of the animal the gall bladders came from. This was precisely the question turned up during the investigations. Under the Indian wild-life protection act 1972, the Himalayan brown bear figures among these schedules. Thus if the gall bladders came from the Himalayan brown bear as the airport police suspected, the Sravan kumar should have been prosecuted under the law. Actually drugs made from gall bladders are used in Tibetan medicine as cure for various ailments which includes joint aches, rheumatism, cataracts, gall stones, cancer and even as aphrodisiacs. Since these drugs are highly reputed (despite their being actually useless), the intact gall bladders of bears sell in the international markets at phenomenal rates. This has caused poaching of bears and consequent fall of bear population. Sravan kumar understood that he had been caught red-handed. The best way to circumvent the law was to deny that these where bear gall bladders. Consequently he asserted that the gall bladders where taken from pigs and not from bears. Since pig not in protected act- Sravan could go scot free. He banked upon the fact that the gall bladders of large mammals look alike and is extremely difficult to distinguish one from another. In effect question belonged to pigs or to bears. It was at this stage that the airport police asked for my help. Despite common belief forensic science doesn’t cater only on solving murders, killings or assassinations. Forensic science is the application of scientific knowledge to solve any legal dispute. Since here the police did face a legal dilemma, forensic science could come to their rescue. During recent years the law enforcement agencies involved in protecting wildlife are increasingly turning to forensic science to bring culprits to the book. Protected animals are killed because of false beliefs in curative powers of medicines made from their body parts, or because of their valuable fur’s or hides or just because for plain fun. Poaching of elephants for ivory is a common problem. But ivory comes from a number of sources ( as many as fifteen ) and often even the criminals find it convenient to assert that ivory came from valid source. In US for instance trading in ivory is illegal, trading in ivory of now extinct mammoths and mastodons. There is synthetic ivory too which is plastic like material. Whenever smugglers are caught with ivory their standard answer is that ivory is from a mammoth which is completely legal. Forensic science once again comes to the rescue of wildlife officers. It helps in differentiating ivory coming from various sources. Mammoth ivory is usually darker than elephant ivory, since it contains traces of iron which has oxidized over time, but is not always the case. The best way ivory from various sources can be distinguished is by observing what are known as Schreger lines. Ivory is criss – crossed by dentinal tubules, which can be seen under a scanning electron micro – scope (SEM) as straight lines. These tubules where first described by a German research Schreger, after whom these lines are named. Thses schreger lines form a unique pattern in each species. For instance while in elephants, these lines always meet an angle greater than 110 degrees., in mammoths they form a very convenient for differentiating between the ivories of mammoth and elephants. Q1). What was the question that turned up during the investigations that followed the confiscation of gall bladders? a) Can experts easily distinguish between animal gall bladders and shriveled mangoes. b) Can experts easily distinguish between the gall bladders of bear and that of pig’s c) It is a matter of experience or of medical expertise that enables doctors to identify the species of the animals to whom the gall bladders belong. d) Is the police force better than the doctors at identifying the species of the animals to whom the gall bladders belong to. e) Is forensic science of any help in identifying the species of the animals from whom the gall bladders have come Q2). Why did Sravan kumar say that gall bladders have been taken out of pigs? i) Because pigs do not figure among the five schedules in the Indian wild-life protection act of 1973. ii) Because he wanted to avoid prosecution iii) Because he did not consider it morally wrong to say so iv) Because he had bribed an forensic scientist to support his statements a) I only b) I & ii only c) I, ii & iii only d) I, ii, iii & iv only Q3). Why are the gall bladders of bears smuggled? i) Because they fetch lot of money ii) Because they are apparently useless iii) Because they are used for making drugs a) I only b) Ii only c) I & ii only d) I & iii only e) Iii only Q4). Which of the following statements is correct ? a) The weired looking things are shriveled black mangoes b) The ‘ursus arctos is abellinus’ is a protected species c) The gall bladders of bears do not sell in the international market d) Sravan kumar was not a smuggler e) Sravan kumar was able to go scot-free by convincing the authorities that the gall bladders came from pigs Q5). What did Sravan kumar base his hopes on? a) The lack of expertise in the field of forensic science b) The fact that the gall bladders had been taken from bears and from pigs c) The fact that the gall bladders of large mammals look alike d) The fact that the intact gall bladders sell in the international market e) The fact that the forensic science is known to cater to solving murders, killings or assasinations Q6). Why did the airport police seek the author’s help? a) Because he is a detcetive b) Because he is a lawyer with extensive knowledge in the field of wildlife protection c) Bnecause he is an expert in the field of forensic science d) Because he is a foreigner setlled in India e) Because he is a great champion of wildlife protection in India Q7). What was the legal dilemna? a) Whether ro prosecute Sravan kumar or to let him go scot-free b) To detremine whther the gall bladders belonged to bears or pigs c) To decide whether bear is an endagered species d) To decide whether pig is an endangered species e) To determine whether forensic science aid should be sought only to solve murders ot to solve any legal disputes Q8). Who are the culprits who need to be punished ? i) Poachers ii) Those who kill animals for their organs iii) Those who hunt protected animals for fun a) I & II only b) I only c) I & III only d) II only e) I, II & III only Q9). Why is it convenient for criminals to claim that ivory has come from valid source? a) Because mammoths and mastodons have become exticnt b) Because ivory comes from as many as fifteen sources c) Because it is possible for one to distinguish between one kind of ivory to another d) Because of elephants is prohibited in many countries e) Because mammoths have tasks which are very similar to synthetic ivory Q10). What is the best way of distinguishing ivory coming from various sources? a) By testing whether the ivory contains traces of iron b) Bvy scrutinizing it closely to see that it is darker than elephant ivory c) By over serving the pattern of tubules on the ivory d) By feeling the texture to note the difference e) By extracting the tissue and getting it examined by a forensic sciebtist

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