Physics Questions

Board 5 In the given LR circuit switch S is closed at t 0 The energy stored in the magnetic field 3L at time to In2 is 2R 1 2 S V L 4R V L L R L reellee 2 4 V L 2R 2R V L PA6 24 HOM

2 It is given that angular momentum of an electron in a particular orbit of hydrogen like atom of atomic number Z is L Assuming Bohr s model and angular momentum quantisation to be true what will be magnitude of total energy of electron for this particular orbit 1 3 m2 e4 32n L 2 2 m22 2 4 m2 87 32 m z 4 8 32 37

3 Two immiscible liquids of density 4 gm cm 6 gm cm are mixed such that their volumes are same What will be density of mixture A B C D 4 gm cc 5 gm cc 6 gm cc 7 gm cc

marks The system shown in the figure is initially at origin and is moving with a constant velocity 5m s k A force F 120t i acts on mass m2 here F is in Newton and time t is in seconds The man throws a light ball at instant when m starts slipping on m2 with a velocity 10 m s vertically up with respect to him self Taking the mass of each block and man as 60 kg and assuming that the man never slips on m The coefficient of fric between m and m is 0 2 There is no friction between m and ground Neglect the dimensions of the system The time at which man throws the ball is 3 sec y A I Projection velocity of ball with respect to ground is 31 10j 5k Projection velocity of ball with respect to ground is 1 5i 10j 5k OZ coordinate of the point where ball lands is 25 m I X man m m 0 2 Smooth Save

The maximum angle to the horizontal at which a stone can be thrown so that it always moves away fr the thrower will be atfavi v 37fdcbqTH fb u U U Uret th ch bd TIf Us g th a ER T A sin 1 C sin 2 3 1 B sin 1 D sin 1 2 2 3

Is given that g H Hz Find angle made by the ray of light with the normal in medium of refractive index 3 1 i 3 sin sini LL Air air H H3 2 sin 4 sin sini Hy sini

3 A light of frequency 10 0 Hz is incident on a photosensitive material The given frequency is 2 5 times of Threshold frequency If above incident frequency is made one third and intensity made five times the photocurrent becomes 1 Five times the initial photocurrent 2 One third the initial photocurrent 3 Three times the initial photocurrent 4 Zero

2013 Consider a finite insulated uncharged conductor placed near a finite positively charged conductor The uncharged body must have a potential A less than the charged conductor and more than at infinity B more than the charged conductor and less than at infinity C more than the charged conductor and more than at infinity D less than the charged conductor and less than at infinity

netic susceptibility of a 2 0 75 3 1 67 angent galvanometer is netic moment M is found y twice that of magnet B and same moment of vibration magnetometer 8 1 Depends on strength of magnetising field 2 Depends on the external condition such as temperature 3 Cannot be done beyond the saturation point 4 All of these A Gaussian surface is drawn enclosing N pole of a bar magnet The net magnetic flux through the Gaussian surface will be pole strength of N pole is treated as positive and S pole as negative 1 Positive N S Gaussian surface 2 Negative perpendic 3 Less and less vertically downwa horizontal at magnetic pole 4 Less and less vertically up horizontal at magnetic pole Soft iron is used to manufa because 1 It has high permeabili 2 Its retentivity and co 3 Its retentivity and 4 Both 1 2 A long solenoid h iron core of u flows in the c beyond curie Positive or negative 4 Zero A material when heated suddenly changes ir property at a particular temperature and its susceptibility is found hure the absolute 1 The Ha zero 2 The unch 3 TE

A convex lens is used to form an image of an object on a wall By moving the lens 40 cm nearer to the wall a sharp image is again obtained having one quarter the length of the first image Focal length of lens is 40 cm 40 cm 20 cm 80 3 cm

When light of maximum wavelength 300 nm falls on a photoelectric emitter photoelectrons are liberated For another emitter however light of maximum wavelength 600 nm causes photoelectric emission The ratio of work functions of first emitter to second emitter will be 1 2 2 1 1 1

3 May increase or decrease in size 4 Have no relation with the field A paramagnetic material is kept in a magnetic field The field is increased till the magnetisation become constant If the temperature is now decreased the magnetisation 1 Will increase 2 Decrease 3 Remain constail 4 May increase or decrease Which of the following four graphs may best represent the current deflection relation in a tangent galvanometer 19 1 3 36 sec 3 9 sec A magnet ma place where intensity is 0 made per se place where of the field i 1 0 157 H 3 0 314H manne

alvanometer is magnet The magnetic field the coil The 2 625 A m 3 125 A m 4 425 A m A ferromagnetic material is placed in an extern magnetic field The magnetic domains 1 Increase in size 2 Decrease in size 3 May increase or decrease in size clation with the field

7 Consider a radioactive substance which decays following the law of disintegration At an instant t its activity is R and at time t it becomes Find 1 R the average life of radioactive substance if t t in R 1 2 2ln R t 2 t In R 3 t 2 t 1 2ln R 4

A body covers half of its journey with speed 20 km h and rest half of its journey with 40 km h What will be the average speed of this journey 320 km h 40 km h ad du al 1 36 66 km h 2 26 66 km h 3 30 km h 4 35 km h ZIEI

59 A uniform disc of radius R 2 3 m is moving on a horizontal surface without slipping At some instant its angular velocity is 1 rad s and angular acceleration is a 3 rad s TT C A 0 B P 777777 Re da a Find acceleration of the top point A b Find acceleration of contact point B c Find co oridnates r 0 for a point P which

7 A wire has a mass 0 3 0 003 g radius 0 5 0 005 mm and length 6 0 06 cm The maximum percentage error in the measurement of density is 0 3 0 003 g 6 0 06 cm 14 1 1 2 2 0 5 0 005 mm 3 3 4 4

The mass defect in a nuclear fusion reaction is 0 05 What amount of energy will be librated in one kg fusion reaction 1 45 102 J 2 45 10 2 eV 3 45 10 J 4 45 10 2 KJ x

An achromatic convergent system of focal length 20 cm is made of the lenses in contact of materials having dispersive powers in the ratio 1 2 Their focal length must be respectively 1 10 cm 20 cm 2 20 cm 10 cm 3 10 cm 20 cm 4 20 cm 10 cm

8 A swimmer can swim in still water at a speed of 15 km h A river is flowing at 5 km h The swimmer starts from a point and swim 1 km upstream and then returns by swimming downstream back to original position During this the average speed of his her swimming is 1 20 3 km h 2 10 km h 40 3 km h 1 km 4 20 km h 11 15 4

The maximum value of index of refraction of a material of a prism which allows the passage of light through it when the refracting angle of the prism is A is A 1 2 40 4 2 1 005 2 1 sin cos V 2 3 1 tan 2 A 4 2 1 cot A 2

Match the corresponding entries of column 1 with column 2 Where m is the magnification produced by the mirror Column 1 A B C D m 2 1 2 m N N m 2 m 1 2 a b c d Column 2 Convex mirror Concave mirror Real image Virtual image 1 Ab and c B b and c C b and d Da and d 2 Aa and c Ba and d Ca and b D cand d 3 Aa and d B b and c Cb and d D b and c 4 Ac and d Bb and d Cb and c Da and d

The following four wires are made of the same material and are at the same temperature Which one of them has highest electrical resistance 1 Length 50 cm diameter 0 5 mm 2 Length 100 cm diameter 1 mm 3 Length 200 cm diameter 2 mm 4 Length 300 cm diameter 3 mm 1 2 3 4

The electric resistance of a certain wire of iron is R If its length and radius are both doubled then 1 The resistance will be doubled and the specific resistance will be halved 2 The resistance will be halved and the specific resistance will remain unchanged 3 The resistance will be halved and the specific resistance will be doubled 4 The resistance and the specific resistance will both remain unchanged 1 2 3 4

A solid metallic sphere has a charge 3Q Concentric with this sphere is a conducting spherical shell having charge Q The radius of the sphere is a and that of the spherical shell is b b a What is the electric field at a distance R a R b from the centre 4Q A 2 R 3Q B TEOR 4 ER C 3Q 2 R Q D 2TEOR

Aakash Rank Booster Test Series for NEET 2020 26 For nuclear stability consider the reaction of a nucleus zXA 2 YA e v If My and My are the masses of the atoms X and Y the reaction name and Q value will be respectively 1 Negative B decay Q Mx My m c 2 Positive B decay Q Mx My m c 3 Negative B decay Q Mx My 2m c LAY 200 2m 2

A human body excretes certain material by a law similar to radioactivity The body excretes half the amount injected in 24 h Find the time in which activity falls to 3uCi in hours if a person is injected technetium t 2 6h and its activity just after the injection is 6uCi Two conducting sphere of radius R are placed at a large distance from each other They are

3 A particle is thrown in air following trajectory y ax 3x where a and B are constant x and are horizontal line and vertical line respectively It s angle of projection maximum height 4x B 1 tan a Ans 2 Sol For Ymex X Ymay 20 Hmay dy dx 8 23 x 0 ax 2 tan a RED INS 8 3 tan 3 a 4 tan B B 4a an

4 Both 1 and 2 10 An astronomical telescope has magnification 8 for normal adjustment A person using this telescope finds that when distance between objective and eyepiece is made 40 cm the final image is formed at infinity Select the correct pair of focal lengths of objective and eyepiece respectively of 5 cm from the lens 40 1 f cm fe 9 9 2 f 10 cm f 30 cm 3 f 320 9 cm fe 320 cm 40 STENG DITE 9 4 f 30 cm f 10 cm cm

If the kinetic energy of a body is increased by 300 its momentum will increase by 1 100 150 200 400 3 Correct Answer 1

7 The charge flown through a circuit in the time interval between t and t dt is given by dq e t dt where is a constant Find the total charge flown through the circuit between t 0 to t t

Employ Norton s theorem to reduce the network connected to RL to o two components b Calculate the downward directed current flow through RL if it is a 3 3k ohms resistor c Verify your answer simulating both circuits with PSpice or a comparable CAD tool 300 mA 5 kn www 7k0 1k0 25V 6kf

Figure shows a container having liquid of variable density The density of liquid varies as p Po 4 3h Here ho and p are ho constants and his measured from bottom of the container A solid block of small dimensions whose density is Po and mass m is released from bottom of the tank fakaf aa chi za wzu fy gy qa s cefa P Po 4 3 3h ho qkaffa sta 31 us ho au po Audig ay h a fuga y dla ch much do I GA ho A The block moves to top and remains at rest at the top 2 fa ga am eff qz faz haze zga B The block will execute SHM T ofa z Correct Answer C D ho The block will be in equilibrium at h 2 e am ho 2 Correct Answer h Time period of the motion of the block 5ho 6g T 27

33 Two bodies A and B each of mass 100 gm are allowed to move along a frictionless typical path as shown below In order to have the same kinetic energy for both the bodies at M the initial velocity that should be given to B if A starts from rest is 2 2m s 1 10 m s 3 11 m s 4 10 2 m s

20x10 4 Two different instruments say guitar ar harmonium playing same music the sound appears different though they pla same frequency because they have different loudness 2 they are played by different person and hence difference in tuning they have different quality 4 they create different pitch x

diodes D D and D3 are ideal for the following potential of A and B The correct increasing order of resistance between A and B will be R 4 D D R Kww D i 10 V 5V ii 5V 10V ii 4V 12V R ww 1 i ii iii 3 ii iii R ww 2 iii ii i 56049 www CON R 4 B

The two slits at a distance of 1 mm are illuminated by the light of wavelength 6 5 10 m The interference fringes are observed on a screen placed at a distance of 1 m The distance between third dark fringe and fifth bright fringe will be 1 0 65 mm 3 3 25 mm 2 1 63 mm 4 4 88 mm

n a standard YDSE arrangement d 3 mm D 1 m and wavelength 1 mm Plane wave is incident normally on the slits as shown Then L Screen 1111 A B C D y coordinate of first order maxima is 15 15 cm y coordinate of first order maxima is 35 35 cm Number of maxima excluding at infinity on screen is 5 Number of minima on screen is 6

The system shown in the figure below consists of a light inextensible cord light frictionless pulleys and blocks of equal mass Notice that block B is attached to one of the pulleys The system is initially held at rest so that the blocks are at the same height above the ground The blocks are then released Find the speed of block A at the moment the vertical separation of the blocks is h Use any variable or symbol stated above along with the following as necessary g

solid sphere of mass 1 kg is tied with a light string to a smooth vertical wall as shown in ne figure A The normal reaction exerted by wall to sphere is 10 N 3 The normal reaction exerted by wall to sphere is 10 2 N C The tension in the string is 10N O The tension the string is 10 2 N

There are three block A B and C of mass 1 kg 2 kg and 3 kg are shown in figure If 15 and 6 N force apply on A and C block Assume surface is smooth 25 26 15 N A 1 kg Find the acceleration of system 3 A m s along east 2 C m s along east 3 B 2 kg C 3 kg 6 N 3 B m s along west D m s along west 2 m s 3 Find the ratio of normal force b w A and B to normal force b w B and C 7 9 6 2

Consider a unit cube which is acted upon by an equal tensile force of F on all the six surfaces of the cube The increase in the length of each side is F xoF fount to be where Y o are Y Y Young s modulus and Poisson s ratio respectively Now Find the value of X 6 Correct Answer

A scaffold of mass 79 kg and length 7 6 m is supported in a horizontal position by a vertical cable at each end A window washer of mass 67 kg stands at a point 1 6 m from one end What is the tension in a the nearer relative to the person cable and b the farther relative to the person cable

4 A bucket tied at the end of a 1 6 m long string is whirled in a vertical circle with con stant speed What should be the minimum speed so that the water from the bucket does not spill When the bucket is at the highest position Take g 10 m sec A 4 m sec B 6 25 m sec C 16 m sec D None of the above

a d c c Ca 4 d Ho 2 2 M 4t d EN Which of the four graphs may best represent the current deflection relation in a tangent galvanometer 2 971 b o 2 M 4 T d 40 d Ho 2M 4 d b a b a d b i 11 4 In a permanent magnet at room temperature a magnetic moment of each molecule is zero of the a If th b If c d e A 2

22 Two similar small balls of mass m and charge q each are suspended by silk strings having length l according to the figure If in the figure 0 is a very small acute angle then for equilibrium the distance between centre of balls is 1 3 q l 2TE mg 9 3 Ema 2 4 edical 117 Divisions of q l 21 mg q l 4 mq 2 12 2

13 It is observed that as one moves along posit x axis the electrostatic potential reduces One n conclude that the direction of electric field 1 Must be along x axis 2 Must be perpendicular to x axis 3 May be perpendicular to x axis 4 May be along x axis

y Chemical Kinetics production in Flowering plants Human Reproduction YSICS JEE Founda The equivalent capacitance between points A and B Services Limited as of five identical capacitors of capacitance 2 F as shown in the figure will be A 2 F HH 1 4 F 3 1 F 2 F 2 F 2 F 2 F B 2 2 F 4 10 F

Q4 A 0 5 kg block slides from A on horizontal track with an initial speed of 3 ms towards a weightless horizontal spring of length 1 m and force constant 2Nm The part AB of the track is frictionless and the part BC has the coefficient of static and kinetic friction as 0 22 and 0 20 respectively If the distance AB and BD are 2 m and 2 14 m respectively the total distance through which the block moves before it comes to rest completely is A A B C D 2 5 m 4 42 m 4 24 m 2 44 m 0 5 kg 3ms B D k 2Nm 0000 C

3 90 V 4 60 V 16 In a certain region potential is given by V k 2xy The electric field at 1 1 has magnitude 1 2 k 2 2 2 k 4 k k 2 17 The variation of electrostatic potential as a function 3 Medical