QUESTION AND ANSWERS

Chemistry and Physics CET Question Papers

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THE CHEMICAL ELEMENTS SORTED BY NAME IN AN ALPHABETICAL ORDER

Element name	Element symbol	Atomic number
Actinium	Ac	89
Aluminium	Al	13
Americium	Am	95
Antimony	Sb	51
Argon	Ar	18
Arsenic	As	33
Astatine	At	85
Barium	Ba	56
Berkelium	Bk	97
Beryllium	Be	4
Bismuth	Bi	83
Bohrium	Bh	107
Boron	B	5
Bromine	Br	35
Cadmium	Cd	48
Caesium	Cs	55
Calcium	Ca	20
Californium	Cf	98
Carbon	C	6
Cerium	Ce	58
Chlorine	Cl	17
Chromium	Cr	24
Cobalt	Co	27
Copernicium	Cn	112
Copper	Cu	29
Curium	Cm	96
Darmstadtium	Ds	110
Dubnium	Db	105
Dysprosium	Dy	66
Einsteinium	Es	99
Erbium	Er	68
Europium	Eu	63
Fermium	Fm	100
Flerovium	Fl	114
Fluorine	F	9
Francium	Fr	87
Gadolinium	Gd	64
Gallium	Ga	31
Germanium	Ge	32
Gold	Au	79
Hafnium	Hf	72
Hassium	Hs	108
Helium	He	2
Holmium	Ho	67
Hydrogen	H	1
Indium	In	49
Iodine	I	53
Iridium	Ir	77
Iron	Fe	26
Krypton	Kr	36
Lanthanum	La	57
Lawrencium	Lr	103
Lead	Pb	82
Lithium	Li	3
Livermorium	Lv	116
Lutetium	Lu	71
Magnesium	Mg	12
Manganese	Mn	25
Meitnerium	Mt	109
Mendelevium	Md	101
Mercury	Hg	80
Molybdenum	Mo	42
Neodymium	Nd	60
Neon	Ne	10
Neptunium	Np	93
Nickel	Ni	28
Niobium	Nb	41
Nitrogen	N	7
Nobelium	No	102
Osmium	Os	76
Oxygen	O	8
Palladium	Pd	46
Phosphorus	P	15
Platinum	Pt	78
Plutonium	Pu	94
Polonium	Po	84
Potassium	K	19
Praseodymium	Pr	59
Promethium	Pm	61
Protactinium	Pa	91
Radium	Ra	88
Radon	Rn	86
Rhenium	Re	75
Rhodium	Rh	45
Roentgenium	Rg	111
Rubidium	Rb	37
Ruthenium	Ru	44
Rutherfordium	Rf	104
Samarium	Sm	62
Scandium	Sc	21
Seaborgium	Sg	106
Selenium	Se	34
Silicon	Si	14
Silver	Ag	47
Sodium	Na	11
Strontium	Sr	38
Sulfur	S	16
Tantalum	Ta	73
Technetium	Tc	43
Tellurium	Te	52
Terbium	Tb	65
Thallium	Tl	81
Thorium	Th	90
Thulium	Tm	69
Tin	Sn	50
Titanium	Ti	22
Tungsten	W	74
Ununoctium	Uuo	118
Ununpentium	Uup	115
Ununseptium	Uus	117
Ununtrium	Uut	113
Uranium	U	92
Vanadium	V	23
Xenon	Xe	54
Ytterbium	Yb	70
Yttrium	Y	39
Zinc	Zn	30
Zirconium	Zr	40

CHARGE-COUPLED DEVICES (CCD)

A charge-coupled device (CCD) is a kind of device that is widely used for such diverse applications as computer memories and image recording. The charge-coupled device employs an array of metal-oxide contacts, as illustrated in Fig. 14.25. Assuming a p-type semiconductor, each of them has a positive imposed potential to create an inversion layer just inside the semiconductor.

Scattering of electromagnetic waves

The third important phenomenon that affects wave propagation is scattering. Scattering results from what are, effectively, elastic collisions between the photons of the incident beam and particles or heterogeneities in the material, causing the photons to be deflected, or scattered, so that they propagate in some new direction. Scattering subtracts intensity from the transmitted wave and contributes to its attenuation. The material property that governs scattering is called the scattering coefficient, S. A wave that is transmitted through a medium with scattering coefficient, S, is attenuated according to the relation

Optical glass and gemstones

Optical glasses serve a number of different functions. Some, like window glass, are intended to maximize transparency. Others, like "crystal" glassware, are intended both to reveal what is contained and to add a certain luster to it. Still other glasses are colored, often for cosmetic reasons, but sometimes to filter light, as in tinted sunglasses and windshields.

Ferrimagnetism

Ferrimagnetism occurs in polyatomic compounds that contain ions with different core magnetic moments. The core magnetic moments order in an antiferromagnetic pattern, but, since alternate moments differ in magnitude, they do not cancel. The material has a net ferromagnetic moment.

The most important of the ferrimagnetic materials are the ferrites , which have the composition MFe2O4, where M is a divalent metal ion. The most familiar of these is magnetite, Fe3O4, which is the historic lodestone that was the first known ferromagnetic material. The ferrites crystallize in the spinel structure. While I shall not attempt to draw it here, it is a relatively simple structure that has a close-packed, FCC arrangement of oxygen atoms with metal ions in 1/2 of the octahedral interstitial sites and 1/8 of the tetrahedral sites. Since there are 2 tetrahedral and 1 octahedral void per oxygen ion, there are 2 metal ions in octahedral sites for each ion in a tetrahedral site. The magnetic order is an antiferromagnetic order in which the moments of all of the octahedral ions are oriented in one direction, while those of all the tetrahedral ions are oriented in the opposite direction.

What is Magnetostriction

Almost all ferromagnetic materials exhibit the phenomenon of magnetostriction in which the material spontaneously expands or contracts in response to a magnetic field. The phenomenon is due to the fact that the material can ordinarily increase its local magnetization slightly by expanding or contracting to optimize the separation of its ion cores. The sign and magnitude of the magnetostriction depends on the material.

Magnetostriction is a useful property that permits a time-varying magnetic field to be converted to a mechanical signal, or vice versa. It is used in transducers and in small speakers for consumer electronics, among many other applications. While nickel was the principle material of choice for early magnetostrictive devices, ferrites are often preferred today since their high resistance minimizes losses due to induced electrical currents.

The magnetic behavior of a type II superconductor

The negative interfacial tension between the normal and superconducting phases is responsible for the unique magnetic behavior of type II superconductors. When ß < 0 the material is driven to create as much interface as possible, and can do so by spontaneously subdividing into a two-phase mixture. The two-phase mixture persists over a range of conditions (in our case, a range of H to either side of Hc) since the subvolumes of the high-energy phase can be made so small that the interfacial tension dominates the free energy. There are, however, limits on how small the regions of normal metal can be. These set upper and lower bounds on the magnetic field that produces the mixed state.

THE CRITICAL CURRENT

ABOUT THE CRITICAL CURRENT

The current-carrying capacity of a superconductor is limited by the critical current density, jc. The critical current of a type I superconductor is set by the critical field; the current induces a magnetic field that adds to the applied field, and the total cannot exceed the critical field. In fact, this limit is not very restrictive unless the applied field is already a considerable fraction of Hc. As we show below, type I conductors can carry very high current densities without inducing fields that approach Hc. Their use in magnets and motors is restricted by the low value of Hc rather than by the field-free critical current.

The critical current of a type II superconductor is set by a completely different mechanism that may limit it to a very small value. When the conductor is in the mixed state, the current imposes a force (the Lorentz force) on the magnetic vortices that thread through it. If the vortices move in response to this force their motion produces an electrical resistance. For this reason, a pure, perfect type II conductor becomes resistive as soon as it enters the mixed state, at Hc1, and is even less useful than a type I superconductor. However, the vortices are linear features that interact with microstructural defects such as precipitates and grain boundaries. Just as microstructural defects pin dislocations and increase strength, they also pin superconducting vortices so that there is a finite critical current in the mixed state. The technologically useful type II superconductors have microstructures that are engineered to provide the strong vortex pinning needed to support high critical currents at high fields.

What is magnetic effect of electric current?

An electric current passing through the coil produces magnetic field around it. This effect is called magnetic effect of electric current.

State flemings night hand rule?

Arrange the first three fingers of your right hand mutually perpendicular to each other. If fore-finger indicates magnetic field, thumb indicates motion of conductor, then second finger indicates the direction of induced current flowing through the conductor.

Define Electro magnetic induction.

Rate of change of the magnetic field linked with the coil induces on e.m.f in the coil. This is called electro magnetic induction.

What are the uses of ultrasound waves?

1.Study of ultrasound waves through a medium reveals physical properties like elasticity, configuration of atoms.
2. Used to detect cracks and flows in metal mouldings
3. Used in mixing of immiscible liquids.
4. used in the manufacturing of alloys.
5. used in drycleaning.
6. used as insect repellants
7. used in sterilization.
8. used to cure neuralylic and rheumatic pains.
9. used in bloodless surgery.
10. used to break gallstones.

What is doppler effect?

Answer: The apparent change in the frequency of a sound wave or light wave when there is relative motion between the source and the observe is called Doppler effect.

A. J.C Doppler discovered doppler effect

Why is ultrasound scanning is preferred over x-rays?

Answer: Ultrasound waves are less harmful when compared to x-rays

What is ECG?

It is a technique to examine heart by ultrasound waves called Echo cardiogram.

Write the relation ship between speed, time and distance of sound waves.

d=vt d=distance of the object from sonar v= velocity of ultrasound wave in water t = time interval between transmission and reception of ultrasound waves.

SOUND QUESTIONS AND ANSWERS

1. Why is study of sound important?
Answer:. Study of sound helps us to know how speech is produced
there by to correct speech impairment.

2. What is an echo?
Answer: A Sound heard after reflection from a rigid surface is called Echo.

3. What is Audible range?
Answer: 20 HZ to 20000HZ

4. What is infrasonic sound.
Answer: A sound of frequency less that 20HZ is called infrasonic sound.

5. What is ultrasonic sound?
Answer: A sound of frequeny greater than 20000 HZ is called ultrasonic sound.

6. Name some animals which can produce ultrasound.
Answer: Bats, Dolphines, dogs

7. Name some animals which can here ultrasound.
Answer: Bats, Dolphines.

8. Why the energy of ultrasound is high?
Answer: Because of high frequency.

9. What is SONAR
Answer: Sonar stands for “SOUND NAVIGATION AND RANGING”

10. What are the uses of sonar?
Answer: 1. To measure depth of sea.
2. To locate underwater objects.

11. Which are the two parts of Sonar?
Answer: 1. Transmitter 2. Detector

12. What is the function of transmitter in SONAR?
Answer: A Transmitter produces ultrasound waves and transmits them in to the water all around.

13. What is the function of detector in SONAR?
Answer: A detector detector the reflected ultrasound waves and coverts it to electrical signals

14. What is persistence of hearing?
Answer: The sensation of sound persists in our ear for about 0.15, this is called persistence of hearing.

15. What is the minimum distance from the obstacle to hear a clear echo?
Answer: 17m

16. When can we here a multiple echo?
Answer: If the sound reflects from the number of reflecting surface then we can hear multiple echos.

17. How do we hear thunder?
Answer: We hear thunder by the multiple reflections of sound from many reflecting surface of clouds.

18. When is sound produced.
Answer: Sound is produced by the vibration of bodies.

Define the 5 stages of working petrol engine.

a. Intake stroke:- The vapourised mixture of petrol and air is let in through the inlet value. The outlet value remains closed. Piston moves away from the spark plug.
B. Compression stroke:- Both the values are closed and the mixture of air and petrol is compressed by the piston moving towards the spark plug. Though the compression increases the temperature of the mixture it is not sufficient to ignite the petrol.
c. Power stroke:- The ignition stage and the expansion stage are together called power stroke.
d. Exhaust stroke: Here outlet value opens Piston moves back. The products of combustion gases are pushed out of the cylinder through the exhaust value.

Define the function of Petrol engine.

Spark plug:- The compressed air and petrol mixture is ignited by the sparks produced by the spark plug.
Crank shaft:- crank shaft coverts linear movement into cirular motion.
Carburettor:- In the carburettor petrol and air are mixed in proper proportions.
Outlet valve:- makes the spent gases to go out of cylinder.