NEET-UG 2013 TEST PAPER WITH SOLUTIONS (HELD ON SUNDAY 05 th MAY, 2013)

Transcription

1 9. In Young's double slit experient, the slits are apart and are illuinated by photons of two wavelengths = Å and = Å. t what iniu distance fro the coon central bright fringe on the screen fro the slit will a bright fringe fro one interference pattern coincide with a bright fringe fro the other? () () 8 () 6 (4) 4 ccording to question n = n So n 5 n 6 so iniu n and n are 5 and 6 respectively. X in = n D 5 d = 6 = 6 9. In a coon eitter (E) aplifier having a voltage gain G, the transistor used has transconductance. ho and current gain 5. If the above transistor is replaced with another one with transconductance. ho and current gain, the voltage gain will be : ns. () () 5 G 4 NEET-UG TEST PPE WITH SOLUTIONS (HELD ON SUNDY 5 th MY, ) () G oltage gain = I ().5 G (4) G L g g G. g. G 9. certain ass of Hydrogen is changed to Heliu by the process of fusion. The ass defect in fusion reaction is.866 u. The energy liberated per u is : (given u = 9 Me) ().5 Me ().67 Me () 6.7 Me (4) Me Energy released per u =.866 9Me = Me 4 L ODE-Y 94. In the given ( T) diagra, what is the relation between pressure P and P? P P () annot be predicted () P = P () P > P (4) P < P P = nt T n n T slope P P s > so P P P P 95. The output (X) of the logic circuit shown in figure will be : () X () X. () X. (4) X =. ns. () or (4) X Three blocks with asses, and are connected by strings, as shown in the figure. fter an upward force F is applied on block, the asses ove upward at constant speed v. What is the net force on the block of ass? (g is the acceleration due to gravity) F () 6 g () zero () g (4) g ns. () s block of ass oves with constant velocity so net force on it is zero. v X

2 NEET-UG- 97. In a n-type seiconductor, which of the following stateent is true: () Holes are ajority carriers and trivalent atos are dopants. () Electrons are ajority carriers and trivalent atos are dopants. () Electron are inority carriers and pantavalent atos are dopants (4) Holes are inority carriers and pentavalent atos are dopants. 98. The half life of a radioactive isotope 'X' is years. It decays to another eleent 'Y' which is stable. The two eleents 'X' and 'Y' were found to be in the ratio : 7 in a saple of a given rock. The age of the rock is estiated to be: () years () 4 years () 6 years (4) 8 years X Y (stable) N x N y Nx Nx N N 7 N N N 8 y x y y using N = N e t we have N 8 t N e t = years = 6 years 99. The olar specific heats of an ideal gas at constant pressure and volue are denoted by P and, respectively. If constant, then is equal to : P and is the universal gas. The wavelength e of an electron and P of a photon of sae energy E are related by: ns. () () P () e () P e (4) P e h hc h h P and e p E p E p e. atio of longest wavelengths corresponding to Lyan and aler series in hydrogen spectru is:- ns. () () 9 () 5 7 P () e (4) 7 9 Lyan 5 / 6 5 aler / 4 7 ax. current loop in a agnetic field :- () an be in equilibriu in two orientations, one stable while the other is unstable. () Experiences a torque whether the field is unifor or non unifor in all orientations () an be in equilibriu in one orientation (4) an be in equilibriu in two orientations, both the euilibriu states are unstable., and are three points in a unifor electric field. The electric potential is :- () () E () (4) P P = and = () Sae at all the three points, and () Maxiu at () Maxiu at (4) Maxiu at Electric potential decreases in the direction of electric field.

3 4. rod PQ of ass M and length L is hinged at end P. The rod is kept horizontal by a assless string tied to point Q as shown in figure. When string is cut, the initial angular acceleration of the rod is :- hange in PE = GM GM ODE-Y () g L ns. () P () g L L g L Q () g/l (4) g/l L I g g L 5. wire of resistance 4 is stretched to twice its original length. The resistance of stretched wire would be :- () 6 () () 4 (4) 8 6. The velocity of a projectile at the initial point is i ˆ j ˆ /s. It's velocity (in /s) at point is :- Y () i ˆ j ˆ () i ˆ j ˆ () i ˆ j ˆ (4) i ˆ j ˆ 7. body of ass '' is taken fro the earth's surface to the height equal to twice the radius () of the earth. The change in potential energy of body will be :- () g () g X GM = g 8. stone falls freely under gravity. It covers distances h, h and h in the first 5 seconds, the next 5 seconds and the next 5 seconds respectively. The relation between h, h and h is :- () h = h = h () h = h = h h h () h = 5 (4) h = h and h = h h g 5, h = g h h h 5 and h = g 5 9. bar agnet of length '' and agnetic dipole oent 'M' is bent in the for of an arc as shown in figure. The new agnetic dipole oent will be () M 6 r () M () M (4) M Let agnetic pole strength be then M = In new situation 6 M' = () rsin where r = () g (4) g M M'

4 NEET-UG-. The internal resistance of a. cell which gives a current of. through a resistance of is (). (). ().5 (4).8. r 4. The resistances of the four ars P,Q, and S in a Wheatstone's bridge are oh, oh, oh and 9 oh, respectively. The e..f. and internal resistance of the cell are 7 volt and 5 oh respectively. If the galvanoeter resistance is 5 oh, the current drawn fro the cell will be :- (). (). (). (4).. E. I. r.5 r r. For photoelectric eission fro certain etal the cutoff frequency is. If radiation of frequency ipinges on the etal plate, the axiu possible velocity of the eitted electron will be ( is the electron ass) :- () h / () h /() () h / (4) h / h() = h + v ax v ax h. During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its teperature. The ratio of p v for the gas is :- () () 4 () (4) 5 P T and P = nt gives P / = constant = p = v. The following four wires are ade of the sae aterial. Which of these will have the largest extension when the sae tension is applied? () length = c, diaeter = () length = 5 c, diaeter =.5 () length = c, diaeter = (4) length = c, diaeter = ns. () Y = F / / = F Y F Yr = Which is axiu for = 5 c & diaeter =.5 r I G Total resistance of Wheatstone bridge = (4)() 4 urrent through cell = = 7 =. (5 ) 5 5. The aount of heat energy required to raise the teperature of g of Heliu at NTP, fro T K to T K is :- ns. () () 4 N a k T T () 8 N a k (T T ) () N a k (T T ) (4) 4 N a k (T T ) Nuber of oles in g He = 4 ount of heat energy required to raise its teepratre fro T K to T K = n v T = 4 (T T ) = 8 k N (T T ) 4

5 6. piece of iron is heated in a flae. It first becoes dull red then becoes reddish yellow and finally turns to white hot. The correct explanation for the above observation is possible by using :- () Newton's Law of cooling () Stefan's Law () Wien's displaceent Law (4) Kirchoff's Law We can explain this observation by using T = b Which is Wien's displaceent law. 7. gas is taken through the cycle, as shown, What is the net work done by the gas? P( Pa) ( ) () J () J () J (4) Zero Net work done = rea of triangle = [(7 ) ][(6 ) 5 ] = J 8. The condition under which a icrowave oven heats up a food ite containing water olecules ost efficiently is :- ns. () () Infra-red waves produce heating in a icrowave oven () The frequency of the icrowaves ust atch the resonant frequency of the water olecules () The frequency of the icrowaves has no relation with natural frequency of water olecules (4) Microwaves are heat waves, so always produce heating ODE-Y 9. n explosion breaks a rock into three parts in a horizontal plane. Two of the go off at right angles to each other. The first part of ass kg oves with a speed of s and the second part of ass kg oves with 8 s speed. If the third part files off with 4 s speed, then its ass is :- () 7 kg () kg () 5 kg (4) 7 kg 8 /s /s kg kg 8 /s Fro conservation of oentu (4) = ( ) ( 8) = 5 kg. In an experient four quantities a, b, c and d are easured with percentage error %, %, % and 4% respectively. Quantity P is calculated as follows P = a b cd % error in P is :- () 4% () 4% () % (4) 7% ns. () P = a b cd P P = ± a b c d a b c d = ± ( ) = ± 4%. sall object of unifor density rolls up a curved surface with an initial velocity v. It reaches upto v a axiu height of with respect to the initial 4g position. The object is () Disc () ing () Solid sphere (4) Hollow sphere Fro conservation of echanical energy K v = gh K v v g 4g K The object is disc 5

6 NEET-UG-. plano convex lens fits exactly into a plano concave lens. Their plane surfaces are parallel to each other. If lenses are ade of different aterials of refractive indices µ and µ and is the radius of curvature of the curved surface of the lenses, then the focal length of cobination is 6 () () (µ µ ) (µ µ ) () (4) (µ µ ) (µ µ ) Equivalent focal length is given by f f f eq (µ ) ( ) f eq f eq = µ µ. parallel bea of fast oving electrons is incident norally on a narrow slit. fluorescent screen is placed at a large distance fro the slit. If the speed of the electrons is increased, which of the following stateents is correct? () The angular width of central axiu will be unaffacted. () Diffraction pattern is not observed on the screen in the case of electrons. () The angular width of the central axiu of the diffraction pattern will increase. (4) The angular width of the central axiu will decrease. s speed of electrons is increased so wavelength of electrons will decreases. Therefore the angular width () of the central axiu of diffrection pattern will decrease. 4. For a noral eye, the cornea of eye provides a converging power of 4 D and the least converging power of the eye lens behind the cornea is D. Using this inforation, the distance between the retina and the cornea -eye lens can be estiated to be - ().5 c () 5 c ().5 c (4).67 c For a noral eye, rays coing fro infinity should go the retina without effort when we look at infinity, lens offers iniu power and hence cobination gives 4D + D = 6D. Distance between the retina and the cornea eye has ust be equal to focal length. f = =.67 c 6 5. The upper half of an inclinded plane of inclination is perfectly sooth while lower half is rough. block starting fro rest at the top of the plane will again coe to rest at the botto, if the coefficient of friction between the block and lower half of the plane is given by:- () µ = tan () µ = () µ = tan v = s s rough sooth tan (4) µ = tan s v = Fro work energy theore (W = KE) (g sin)(s) (µg cos)(s) = µ = tan

7 6. wave travelling in the +ve x-direction having displaceent along y-direction as, wavelength and frequency of Hz is represented by : () y = sin (x + t) () y = sin (x t) () y = sin (x t) (4) y = sin (x t) ns. () ODE-Y 9. Two pith balls carrying equal charges are suspended fro a coon point by strings of equal length, the equilibriu separation between the is r. Now the strings are rigidly claped at half the height. The equilibriu separation between the balls now becoe : k = = and = f = () = So equation of wave y = sin(kx t) = sin(x t) 7. source of unknown frequency gives 4 beats/s, when sounded with a source of known frequency 5 Hz, The second haronic of the source of unknown frequency gives five beats per second, when sounded with a source of frequency 5 Hz, The unknown frequency is () 6 Hz () 54 Hz () 46 Hz (4) 4 Hz ns. () Frequency of unknown source = 46 Hz or 54Hz Second haronic of this source = 49Hz or 58 Hz Which gives 5 beats per second, when sounded with a source of frequency 5 Hz. Therefore unknown frequency = 54 Hz 8. coil is self-inductance L is connected in series with a bulb and an source. rightness of the bulb decreases when : () an iron rod is inserted in the coil. () frequency of the source is decreased. () nuber of turns in the coil is reduced. (4) capacitance of reactance X = X L is included in the sae circuit. ~ rightness of the bulb decreases when an iron rod is inserted in the coil as ipedance of circuit increases. increases when frequency of the source is decreased as ipedance of circuit decreases. Increases when nuber of turns in the coil is reduced as ipedance of circuit decreases. increases when a capacitance of reactance X = X L is included in the circuit as ipedance of circuit decreases. () F r r () r g y r/ Therefore y tan = r y / r y r () (4) r F g y/ r / kq y r g y r r' = r /. If we study the vibration of a pipe open at both ends, then the following stateent is not true : () Pressure change will be axiu at both ends () Open end will be antinode () Odd haronics of the fundaental frequency will be generated (4) ll haronics of the fundaental frequency will be generated Pressure change will be iniu at both open ends. 7

8 NEET-UG-. When a proton is released fro rest in a roo, it starts with an initial acceleration a towards west. When it is projected towards north with a speed v it oves with an initial acceleration a towards west. The electric and agnetic fields in the roo are: () () () a e east, a down a e west, a up a e west, a down a (4) e east, a up q cceleration of charged particle a (E v ) q eleased fro rest a E = a (west) E = a (west) e when it is projected towards north, acceleration due to agnetic force = a Therefore agnetic field = a (down). wire loop is rotated in agnetic field. The frequency of change of direction of the induced e..f. is : () Six ties per rolution () Once per rolution () twice per rolution (4) four ties per rolution. unifor force of (i j) newton acts on a particle of ass kg. Hence the particle is displaced fro position (i k) eter to position (4i j k) eter. The work done by the force on the particle is :- () 5 J () 9 J () 6 J (4) J ns. () W = F.S (i ˆ ˆj).[(4 )i ˆ ( ) ˆj ( )k] ˆ = (i ˆ ˆ j).(i ˆ j ˆ k) ˆ = () + () + ( ) = 9 J 4. The wettability of a surface by a liquid depends priarily on :- () angle of contact between the surface and the liquid () viscosity () surface tension (4) density 5. Infinite nuber of bodies, each of ass kg are situated on x-axis at distance,, 4, 8,..., respectively, fro the origin. The resulting gravitational potential due to this syste at the origin will be : () 4G () G () 8 G (4) 4 G = G () = G / = 4G 8