APTITUDE AND TECHNICAL QUESTIONS

Mumbai

DEAR FRIENDS! HERE I HAVE INCLUDED SOME APTITUDE AND TECHNICAL QUESTIONS ASKED BY FAMOUS COMPANIES
DURING INTERVIEWS. I HOPE, THIS WILL BE MORE USEFUL TO THE STUDENTS WHO ARE PREPARING FOR
INTERVIEW. SELECT THE QUESTION PAPER YOU NEED FROM THE LIST BELOW.

LIST OF QUESTION PAPERS

TATA CONSULTANCY SERVICES SAMPLE TEST
INFOSYS SAMPLE TEST 1
INFOSYS SAMPLE TEST 2

TATA CONSULTANCY SERVICES

SAMPLE TEST

NOTE:EACH OF THE QUESTIONS GIVEN BELOW APPEAR AS MULTIPLE CHOICE QUESTIONS IN THE ACTUAL PAPER.

VERBAL SECTION

Directions for questions 1-15: Find the synonyms of the following words

1. Depreciation

Ans. Deflation, Depression, Devaluation, fall, slump in value

2. Deprecate

Ans. Feel and express disapproval of

3. Incentive

Ans. Thing one encourages a person to do something

4. Echelon

Ans. Level of authority or responsibility

5. Innovation

Ans. To make changes or introduce new things

6. Intermittant

Ans. Externally stopping and then starting

7. Detrimental

Ans. Harmful

8. Aberration

Ans. Deviation

9. Conciliation

Ans. To make less angry or more friendly

10. Orthodox

Ans. Conventional or superstitious

11. Fallible

Ans. Liable to err

12. Volatile

Ans. Ever changing

13. Manifestion

Ans. Clear or obvious

14. Connotation

Ans. Suggest in addition to the fundamental meaning

15. Reciprocal

Ans. Reverse, Opposite

QUANTITATIVE SECTION

1. There are 150 weights .Some are 1 kg weights and some are 2 kg weights. The sum of the weights is 260.What is the number of 1kg weights?

Ans. 40

2. A is driving on a highway when the police fines him for overspeeding and exceeding the limit by 10 km/hr. At the same time B is fined for overspeeding by twice the amount by which A exceeded the limit. If he was driving at 35 km/hr what is the speed limit for the road?

Ans. 15 kmph

3. A moves 3 kms east from his starting point. He then travels 5 kms north. From that point he moves 8 kms to the east. How far is A from his starting point?

Ans. 13 kms

4. A car travels 12 kms with a 4/5th filled tank. How far will the car travel with 1/3 filled tank?

Ans. 5 kms

5. The sum of the digits of a two digit number is 8. When 18 is added to the number, the digits are reversed. Find the number?

Ans. 35


6. The cost of one pencil, two pens and four erasers is Rs.22 while the cost of five pencils, four pens and two erasers is Rs.32. How much will three pencils, three pens and three erasers cost?

Ans. 27

7. Fathers age is 5 times his son's age. 4 years back the father was 9 times older than son.Find the fathers' present age.

Ans. 40 years

8. What number should be added to or subtracted from each term of the ratio 17 : 24 so that it becomes equal to 1 : 2.

Ans. 10 should be subtracted

9. What is the 12th term of the series 2, 5, 8, ....

Ans. 35

10. If 20 men take 15 days to complete a job, in how many days can 25 men finish that work?

Ans. 12 days

11. In a fraction, if 1 is added to both the numerator at the denominator, the fraction becomes 1/2. If numerator is subtracted from the denominator, the fraction becomes 3/4. Find the fraction.

Ans. 3/7


12. If Rs.1260 is divided between between A, B and C in the ratio 2:3:4, what is C's share?

Ans. Rs. 560

13. A shopkeeper bought a watch for Rs.400 and sold it for Rs.500.What is his profit percentage?

Ans. 25%

14. What percent of 60 is 12?

Ans. 20%

15. Hansie made the following amounts in seven games of cricket in India: Rs.10, Rs.15, Rs.21, Rs.12, Rs.18, Rs.19 and Rs.17(all figures in crores of course).Find his average earnings.

Ans. Rs.16 crore

CRITICAL REASONING SECTION

This section is basically just a reading comprehension section. The critical reasoning section consists of some passages followed by 4 to 7 questions per passage. The questions are such that they require ability to read fast and comprehend.The questions asked in this section have three choices TRUE, FALSE, CAN'T SAY. Some examples of passages are given in test 1.For further practice you may go through any GRE or CAT book which will provide you with ample practice regarding these kinds of questions.

PYSCHOMETERIC TEST

This test consists of 150 questions and is just a pyshcology test which should be answered confidently and doesn't require any preparation. One must try being consistent while answering as the same questions are repeatedly asked in different forms. Also one must answer all questions. Questions are of yes or no kind.

Example:

Are you sincere?

If you find a purse in the market with loads of money would you return it to the rightful owner?

While climbing up the stairs do you take two steps at a time?

Do you drink and smoke more than you think you should?

Are you the life of the party you attend?

Are you shy?


INFOSYS SAMPLE TEST1

1. At 6'o a clock ticks 6 times.
The time between first and last ticks is 30 seconds.
How long does it tick at 12'o clock.

Ans: 66 sec.


2. Three friends divided some bullets equally.
After all of them shot 4 bullets the total number of bullets remaining is equal to the bullets each had after division.
Find the original number divided.

Ans: 18
Initially . x x x
Now x-4 x-4 x-4
Equation is 3x-12 = x

3. A ship went on a voyage.
After it had travelled 180 miles a plane statrted with 10 times the speed of the ship.
Find the distance when they meet from starting point.

Ans: 200miles.
Distance travelled by plane = 1/10 distance travelled by ship + 180

4. Complete the Table given below:
Three football teams are there. Given below is the group table. Fill in the x's



Ans: The filled table is given below


5. There are 3 societies A, B, C.
A lent cars to B and C as many as they had already.
After some time B gave as many tractors to A and C
as many as they have. After sometime c did the same thing. At the end of this transaction each one of them had 24.
Find the cars each orginally had.

Ans: A had 39 cars, B had 21 cars & C had 12 cars

6. There N stations on a railroad.
After adding X stations on the rail route 46 additional tickets have to be printed.
Find N and X.

Ans. x=2 and N=11
Let initially, N(N-1) = t
After adding, (N+X)(N+X-1) = t+46
By trail and error method

7. Given that April 1 is tuesday.
A, B, C are 3 persons told that their farewell party was on

· A - May 8, thursday
· B - May 10,tuesday
· C - June 5, friday

Out of A, B, C only one made a completetly true statement concerning date,day and month
The other told two one told the day right and the other the date right..
What is correct date, month, day.

Ans: B - (May 10) SUNDAY
C - June 6 (Friday).

8. The Bulls, Pacers, Lakers and Jazz ran for a contest.
Anup, Sujit, John made the following statements regarding results.

· Anup said either Bulls or Jazz will definitely win
· Sujit said he is confident that Bulls will not win
· John said he is confident that neither Jazz nor Lakers will win

When the result cameit was found that only one of the above three had made a correct statement.
Who has made the correct statement and who has won the contest.

Ans: Sujith; Lakers

9. Five people A ,B ,C ,D ,E are related to each other.
Four of them make one true statement each as follows.

(i) B is my father's brother.
(ii) E is my mother-in-law.
(iii)C is my son-in-law's brother
(iv)A is my brother's wife.

Ans: (i) D
(ii) B
(iii) E
(iv) C

10. Some statements are given below:

· L says all of my other four friends have money
· M says that P said that exactly one among them has money
· N says that L said that precisely two among them have money
· O says that M said that three of the others have money
· P, L and N said that they have money

All the above statement are false..

Who has money & who doesn't have any money?


INFOSYS SAMPLE TEST2

1. Replace each letter by a digit.

Each letter must be represented by the same digit and no beginning letter of a word can be 0.

O N E
O N E
O N E
O N E
-------
T E N

Ans: 0 =1, N = 8 ,E = 2, T = 7

2. Ann, Boobie, Cathy and Dave are at their monthly business meeting.
Their occupations are author, biologist, chemist and doctor, but not necessarily in that order.
Dave just told the biologist that Cathy was on her way with doughnuts.
Ann is sitting across from the doctor and next to the chemist.
The doctor was thinking that Boobie was a goofy name for parent's to choose,but didn't say anything.

What is each person's occupation?

Ans: Since Dave spoke to the biologist and Ann sat next to the chemist and across the doctor, Cathy must be the author
and Ann the biologist.
The doctor didn't speak, but David did, so Bobbie is the doctor and Dave the chemist.

3. Sometime after 10:00 PM a murder took place.
A witness claimed that the clock must have stopped at the time of the shooting.
It was later found that the postion of both the hands were the same but their positions had interchanged.
Tell the time of the shooting (both actual and claimed).

Ans: Time of shooting = 11:54 PM
Claimed Time = 10:59 PM

4. Next number in the series is
1 , 2 , 4 , 13 , 31 , 112 , ?

Ans: 224.
No number has digits more than 4. All of them are 1 , 2, 4, 8 , 16 , 32 , 64 converted to numbers in base 5

5. Shahrukh speaks truth only in the morning and lies in the afternoon, whereas Salman speaks truth only in the afternoon. A says that B is Shahrukh. Is it morning or afternoon and who is A - Shahrukh or Salman.

Ans: Afternoon ; A is Salman.

6. Two trains starting at same time, one from Bangalore to Mysore and other in opposite direction arrive at their
destination 1 hr and 4 hours respectively after passing each other. How nuch faster is one train from other?

Ans: Twice

7. There are 6 volumes of books on a rack kept in order ( ie vol.1, vol. 2 and so on ).
Give the position after the following changes were noticed.

· All books have been changed
· Vol.5 was directly to the right of Vol.2
· Vol.4 has Vol.6 to its left and both weren't at Vol.3's place
· Vol.1 has Vol.3 on right and Vol.5 on left
· An even numbered volume is at Vol.5's place

Find the order in which the books are kept now.

Ans: 2 , 5 , 1 , 3 , 6 , 4

8. I bought a car with a peculiar 5 digit numbered licence plate which on reversing could still be read.
On reversing value is increased by 78633.Whats the original number if all digits were different?

Ans: Only 0 1 6 8 and 9 can be readupside down.So on rearranging these digits we get the answer as 10968

9. UNAVAILABLE

10. Supposing a clock takes 7 seconds to strike 7. How mlong will it take to strike 10?

Ans: 10 1/2 seconds.

LINKS

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www.wikipaedia.com.

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OPTICAL FIBER MANUFACTURE

Mumbai

HAI FRIENDS! HERE I HAVE ADDED MY KNOWLEDGE ABOUT OPTICAL FIBER MANUFACTURE!

OPTICAL FIBER MANUFACTURE

INTRODUCTION :

Optical fibers play a vital role in modern communication. If we consider the history of optical fiber, image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s.

In 1952, physicist Narinder Singh Kapany conducted experiments that led to the invention of optical fiber. Modern optical fibers, where the glass fiber is coated with a transparent cladding to offer a more suitable refractive index, appeared later in the decade. Development then focused on fiber bundles for image transmission.
The first fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, and Lawrence E. Curtiss, researchers at the University of Michigan, in 1956.

In 1965, Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables (STC) were the first to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer, allowing fibers to be a practical medium for communication. They proposed that the attenuation in fibers available at the time was caused by impurities, which could be removed, rather than fundamental physical effects such as scattering.

The crucial attenuation level of 20 dB/km was first achieved in 1970, by researchers Robert D. Maurer, Donald Keck, Peter C. Schultz, and Frank Zimar working for American glass maker Corning Glass Works, now Corning Incorporated. They demonstrated a fiber with 17 dB/km attenuation by doping silica glass with titanium. A few years later they produced a fiber with only 4 dB/km attenuation using germanium dioxide as the core dopant. Such low attenuations ushered in optical fiber telecommunications and enabled the Internet.

Attenuations in modern optical cables are far less than those in electrical copper cables, leading to long-haul fiber connections with repeater distances of 50–80 km (30–50 miles).

BASIC PRINCIPLE :

When light traveling in a dense medium hits a boundary at a steep angle (larger than the "critical angle" for the boundary), the light will be completely reflected. This is called Total Internal Reflection.

MANUFACTURING :

There are a wide range of methods available for the manufacturing of optical fibers. All the methods of manufacturing optical fiber has been discussed below.

ROD IN TUBE METHOD:

This is one of the oldest methods of manufacturing optical fiber. It consists of a high quality fused silica rod and fluoride doped silica tube. The rod is placed inside the tube and sent in to a drawing furnace and heated. At the output we get the fiber of required diameter with core and cladding. Then the fiber is rolled on to rotating drum.

DOUBLE CRUCIBLE METHOD :

In this method, two platinum crucibles are placed inside a furnace. Fused silica is laced in the inner crucible and fluoride doped silica is placed in the outer crucible.
Now the furnaces are heated and hence the required fiber with cladding is obtained through the nozzle. This fiber is then rolled on to a rotating drum.
In the above two methods losses are very high. Hence they are not used to manufacture optical fibers.

VAPOUR DEPOSITION METHODS:




Vapour deposition method is most widely used to manufacture optical fiber. The above tree represents the various methods and processes involved in manufacturing optical fiber using vapour deposition method. In these methods perform is developed and then fiber is drawn from them. Let us see the different vapour deposition methods of developing preforms.


INSIDE VAPOUR DEPOSITION :

This process involves four steps. They are,
Forming of glass particles (soot) from the raw materials.
Sinterung of soot to a transparent glass.
Collapsing the tube to forn preform.
Fiber drawing from preform.



OUTSIDE VAPOUR DEPOSITION :

This method was introduced in 1973. It consists of oxygen – hydrogen burner. The burner consists of three orifices. Vapours of sicl4, o2, and dopants are sent through the central orifice. Fuel gas and o2 mixture are sent through the outer orifice. The other orifice is used to produce deposition on the mandrel. Mandrel is nothing but a rod made of Al2o3. The burner moves back and forth and the mandrel is slowly rotated during deposition. Single layer of silica is deposited per pass. Up to 1000 layers can be formed in this method. The deposition is about 80cm in length and 11cm in diameter and weighs 1800g. The deposition rate is 1 to 48 layers per minute.
After cooling the mandrel is removed from the glass soot. Then the porus deposition is vertically passed in to an annular furnace and heated to 1500degree Celsius to produce a dense glass rod. By using He atmosphere with few percentage of chlorine in the furnace, OH ions that produce distortions in the fiber can be eliminated.

VAPOUR PHASE AXIAL DEPOSITION:

In 1977, researches at Nippon telegraph and telephones in Japan introduced this technique. The two main advantages of this method are,







No collapsing is needed.
Highest bandwidth Graded Index Fiber can be obtained.

In this method performs up to 580kms can be drawn. The only difference between OVD and this method is, the deposition is made axially. It has three parts.

A water-cooled stainless steel box as the deposition chamber with the burner and exhaust at the lower part and sintering at the upper part.
The chemical delivery and exhaust systems are same as other methods.
Control system with controllers for position and rotation of perform and for temperature profiling.
The raw materials are vapourised and fed to the burner. The tiny glass particles from the burner are blown to the rotating silica rod. Thus the porus perform is formed during deposition. The distance between burner and perform must be constant to give uniform deposition. This is done by moving the perform upwards. For monitoring this, a video camera is used. The temperature can be measured using thermo viewer. The thermo viewer consists of a scanning pyrometer. The disadvantage of method is, this is not suitable for multiple clad single mode fiber.

MODIFIED CHEMICAL VAPOUR DEPOSITION :

This was developed by bell laboratories in 1974. The raw marerials used in this method are sicl4, Gecl4, Pocl3, Bcl3 or BBr3. Compared to normal CVD, concentration of reagents and temperature are high in this method.
Controlled amount of SiCl4 vapours and dopant along with O2 are fed in to a rotating fused silica substrate. It is heated using a oxy – hydrogen burner to 1600 degree celcius. Thus silica particles are deposited on the inner wall of the substrate. The burner is moved from left to right. When it gets to right end, it moves fast back to the left end. Since deposition takes place only when the burner moves towards the direction of the flow of gases. Refractive index can be by varying gas mixture. Using this method 40 to 100 iayers are formed. Then the tube is collapsed to give the preform.

PLASMA ENHANCED CVD :

It is an extension of MCVD. It combines the advantage of MCVD with large increase in deposition rate. An isothermal plasma (f==3MHZ) at atmospheric pressure is used. This was used first in 1977.
Plasma initiates the chemical reaction. Plasma is instable and hence performance is limited. Nowadays, plasma is used only to initiate chemical reaction and deposit the glass particles. A hydrogen burner is used for sintering process. RF generator and RF coils are additionally needed.
Diameter of the substrate tubes are increased as 46mm inside and 50mm for outside. With RF power of about 12KW, an oxygen RF plasma is built up at normal pressure. The plasma is centered at the glass tube. Its temperature is 10,000 degree Celsius. At the region of plasma, hot spots can be produced on the glass tube, which produces distortion. So, water is used continuously for cooling.

PALSMA ACTIVATED CVD:

Use of plasma for fiber optics was first established in 1975 by a research group of Phillips in Germany. PCVD is also a modification of MCVD. The substrate tube is placed in a stationary furnace at 1200 degree Celsius. Normally, rotation of the tube is not necessary. But practically, it is done in order to prevent distortions due to small temperature changes over the tube. Instead of a burner, a microwave cavity(f=2.5GHZ) traverses the furnace repeatedly. At a pressure of 10 to 50 Hpa, a non-isothermal or cold plasma is generated inside the tube. This initiates the deposition of transparent glass layer on the inner wall. Sintering is redundant. Deposition takes place on both directions. Up to 1000 layers can be deposited. It is more efficient than any other. The deposition is 80% with GeO2 and 100% with SiO2.

PLASMA OUTSIDE DEPOSITION :

This method has been introduced at Germany in 1975. A plasma torch is used for chemical reaction and deposition. Big transparent performs with more than 1kg can be obtained. No sintering or collapsing is needed in this method. The raw materials SiCl4, Cci2F2 and oxygen are fed in to plasma torch at 1800 to 2300 degree Celsius. The fluoride deposited silica are deposited as a transparent glass on the surface of a rotating glass rod (suprasil-W rod). Preforms with 60mm diameter and 200mm length can be fabricated. These performs are made in to rods of &m length and 10mm diameter. Then they are drawn in to fiber. The major disadvantage is OH ions are present in large amount and hence attenuation is high.

DRAWING PROCESS:

Preforms converted to fibers of diameter 100 to 400mm and 125mm is used as standard overall fiber diameter.A polymer coating is done here in order to protect the fiber from humidity and external mechanical forces. During drawing, the refractive index of the preform doesn’t change. The average height if the drawing towers used is 18m.
The maximum temperature of the furnace is 2200 degree Celsius. Temperature is maintained precisely because, a small change in temperature may vary the fiber diameter.

There are two types of furnaces, which are widely used. They are,

Graphite resistance furnace
Zirconium induction furnace
Graphite furnace can be easily controlled. A protective noble gas like argon is needed to prevent any degradation of burning if graphite heater. This noble gas can form fiber distortion.
Zirconium does not need protective gas. But, handling and temperature control is difficult.
In the apparatus for drawing, a diameter monitor is used below the furnace. Varying pulling velocity of the fiber varies diameter. Fiber is coated with a suitable polymer at the intermediate region. If pulling velocity of fiber exceeds 5m/s, the coating bath must be pressurized to minimize shear rates. This avoids slipping of fiber. Heating or applying UV rays then cures the polymer.
If the pulling speed is high, then the height of the tower must also be high. Varying the position of the coating nozzle can vary the coating concentration. Then it is wound through capston to drum.

COMPARISON:

CONCLUSION :

From the above discussions, we may conclude that no method is a perfect one for manufacturing the optical fiber. Depending on the requirements, the type of manufacturing is chosen. More researches are going on regarding manufacture of perfect loss less optical fiber. Nowadays the use of optical fiber have been increased and it may be expected to contribute in most of the communication systems in future.

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