Physics Questions

Problem 4 4 A load cell Fig 4 40 is formed of a hollow steel cylinder loaded axially The four strain gauges are so connected as to enhance the signal and compensate for temperature variation The load cell has a cross sectional area of 2 cm Young s modulus of steel is 2 07 x 10 N m and Poisson s ratio 0 3 Strain gauge resistance 1000 2 I Gauge factor 2 1 310 RR R R A E R R Ra innan R R

A conical container of radius R 1m and height H 5m is filled completely with liquid There is a hole at the bottom of container of area 10 3 m2 see figure Time taken to empty the conical container in sec is 100T Find the value of T

A highly conducting solid cylinder of radius a and length is surrounded by a co axial layer of a material having thermal conductivity K and negligible heat capacity Temperature of surrounding space outside the layer is T which is higher than the temperature of the cylinder If heat capacity per unit volume of the cylinder material is S and outer radius of the cylinder is b time required to increase the temperature of the cylinder from 7 to T is Assume end faces to be thermally insulated and given that b 2a T 500K T 300K T 400K In 2 0 7 Sa n 200K Where n

A rod is kept an angle of 60 with the horizontal by the help of a string in vertical plane The string is now cut at t 0 Find the force in N applied by upper half section of the rod AC on the lower half section of the rod BC just after t 0 Take mass of the rod 6 4 kg and g 10 m s Take 193 13 86 rod String B

Two blocks A and B of masses 2 kg and 8 kg respectively are kept in contact and pressed against a rough vertical wall by applying a horizontal force F 50 N as shown The frictional force acting between the two blocks is A zero B 6N C 8 N D 10 N 50N F A 2 kg H 0 3 H 0 2 B 8 kg 0 7 0 6

34 A ball is thrown vertically down from a certain height with some speed After rebound with ground it is caught at the same point with same speed at which it was thrown Its velocity time v t graph Taking vertically downward direction as positive is best represented by V L 1 2 3 4 0 V t

Choose incorrect statement about electric field lines due to a charge configuration The density of field lines at a point represents proportional strength of electric field at that point They are lines or curves which emerge from O positive charge and terminate at negative charge O They can form a closed loop

Network shown in the diagram is part of an electrical circuit The current is 2 A and is decreasing of 2 Als then V V equals 1 2 V XVM M P 2 V 19 www 2 A 1 H 0000000 2 2 V 4 4 V

A liquid is filled in a large container as shown A source S is moving with constant velocity 3v 4 in upward direction A man A is stationary on the surface of water such that his ear is in the air Another man B is moving downward inside the water with constant velocity v 3 Source emits sound of frequency f Speed of sound in the air is v and in the liquid is 5v Then A Wave length received by man A is 7v 4f 35v 4f B Wave length received by man B is 2f C Frequency received by man A is 7 8f 15 D Frequency received by man B is 3v 4 S A Source

Infinite number of alternate charges q and q are arranged on a straight line with separation a Find interaction energy of each charge with all others ka O q q q q q q 9 9 O q 27a 2q In 2 In 2 39 Ta In2 o 9 9 9

If n 1 is taken to be reference of the potential energy what will be the kinetic energy in eV of an electro in second excited state in Li 1 13 6 eV 3 54 4 eV 2 108 8 eV 4 12 08 eV

39 With an ac input from 50 Hz power line the ripple frequency is a 50 Hz in the dc output of half wave as well as full wave rectifier b 100 Hz in the dc output of half wave as well as full wave rectifier c 50 Hz in the dc output of half wave and 100 Hz in dc output of full wave rectifier d 100 Hz in the dc output of half wave and 50 Hz in the dc output of full wave rectifier In a full wave iunction diode rectifior th d input 14 8 Spe op Dio 44 What h diode a Th C b T

A radioactive sample disintegrates via two independent decay processes having half lives T and T2 respectively The effective half life T1 2 1 2 1 2 of the nuclei is 1 None of the above 2 T1 2 T T 1 2 1 2 3 T1 2 4 T1 2 1 2 1 2 T 1 1 2 T 2 1 2 T t 1 2 7 2 1 2 T T 2 1 2 1 2

un object with a height of 0 06 m points below the principal axis it is Inverted and is 0 140 m in front of a diverging lens The focal length of the lens is 0 26 m Include the sign of the value in your inswers a What is the image distance b What is the magnification m c What is the image height m

In an isolated Li electron jumps from n 2 to n 1 What is the recoil momentum of the ion in kg m s 1 5 44 x 10 27 3 16 32 10 27 2 48 96 10 27 4 8 16 10 27 If n 1 is taken to be reference of the potential energy what will be the kinetic energy in eV of an electro

A pan balance has a container of water with an overflow spout on the right hand pan as shown It is full of water right up to the overflow spout A container on the left hand pan is positioned to catch any water that overflows The entire apparatus is adjusted so that it s balanced A brass weight on the end of a string is then lowered into the water but not allowed to rest on the bottom of the container What happens next Water A Water overflows and the right side of the balance tips down B Water overflows and the left side of the balance tips down C Water overflows but the balance remains balanced

5 Suppose the potential energy between electron and to find velocity and its value will be nh 2kmr 1 V 3 V n h 2xmr oton at a distance r is given by nh 2xmr 4 Can t be found 2 Medica Proton Ke 3r Use Bohr s theor

Determine the wavelength of the first Lyman line the transition from n 2 to n 1 In what region the electromagnetic spectrum does this line lie 1 1 22 x 10 7 m UV region 2 2 78 x 10 7 UV region 4 2 78 x 10 7 IR region 3 1 22 x 10 7 m IR region Figure shows come operoy levels of on stom If the transition 5 to 5 gives emission of ultraviolet radiation

ow the marked expression came sir nergy of electron in the hydrogen atom Total Energy of electron in nth orbit e 8 r KE mv 2 and PE 1 e e 4 0 r 2KE PE 2 KE Total energy of the system KE PE e E 2KE KE KE 8

18 If a piece of metal is heated to temperature and then allowed to cool in a room which is at temperature 00 The graph between the temperature T of the metal and time t will be closed to

A ring of radius R is rolling without slipping over a fixed surfaces It s linear mass density varies as 1 cos0 as shown At the instant shown centre of ring has speed v Find its total kinetic energy in joule Given R 1m v 1 m s o 1 2 kg m R Q 2 2 2 cose

point fre charge A charge Q is uniformly distributed over a large plastic non conducting sheet The electric field at a point close to the centre of the plate near the surface is 20 V m If the plate is replaced by a copper plate of the same geometrical dimensions and carrying the same charge Q then what is the electric field at that point 3x 101NG 1 through a cube of side 20 cm oriented field

28 Two charges each equal to q are kept at x a and x a on the X axis A particle q of mass m and charge q is placed at 2 the origin If charge qo is given a small displacement y a along the Y axis the net force acting on the particle is

9 A mass is released from a height h and its time of fall t is recorded in terms of time period T of a simple pendulum On the surface of earth it is found that t 2T The entire set up is taken on the surface of another planet whose mass is half of earth and radius the same Same experiment is repeated and corresponding times are noted as t and T

In Young s double slit arrangement slits are separated by a gap of 0 5 mm and the screen is placed at a distance of 0 5 m from them The distance between the first and the third bright fringe formed when the slits are illuminated by a monochromatic light of 5890 AA is 9 1 1178 10 m 2 1178 x 10 6 m 3 1178 10 2 m 4 5890 X 10 7 m

The ratio of magnetic moment of an electron to its angular momentum in an atomic orbit will be 2m e 2m 2 E El E

is of be of 23 The of a photocells kept fixed The wavelength of the ligh falling on the cathode is gradually changed The plate current I of photocel varies as follows MS164 a c 1776 2 b 2 2 VL d

1 11 Three identically charged small spheres each of mass m are suspended from a common point by insulated light strings each of length 1 The spheres are always on vertices of an equilateral triangle of length of the sides x 1 Calculate the rate da dt with which charge on each sphere increases if length of the sides of the equilateral triangle increases slowly according dx a dt to law Ans 3reomga

placed vertically as shown A point charge Qo is placed at point O at a distance L from its one end Potential energy of charge Qo is equal to B L A OAQ In2 4180 OAQ In2 200 O AQ 40E0

Speed of an electron in hydrogen atom in 1st orbit is 2 x 100 m s The velocity of an electron in 3rd orbit doubly ionized lithium is 1 5 x 10 m s 3 4 x 10 m s 2 6 108 m s 4 2 x 108 m s

Zero Marks in all outer In shown system strings and pulley are frictionless and massless Block A is moving downward with velocity of 7m s which is increasing at a rate of 2 m s2 while block C is moving upward with a velocity of 9 m s whi decreasing at a rate of 3 m s The block B is moving downward with velocity of v8 m s which is decreasing at a rate of as m s Find the value of Vs as A B C

A constant power delivering machine has towed a box which was initially at rest along a horizontal straight line The distance moved by the box in time t is proportional to 1 t 3 2 t 2 3 t 4 t 2 C

Match List I with List II List I a 10 km height over earth s surface b 70 km height over earth s surface c 180 km height over earth s surface d 270 km height over earth s surface List II i Thermosphere ii Mesosphere iii Stratosphere iv Troposphere 1 a i v b i i i c i i d i 2 a i b iv c iii d ii 3 a iii b ii c i d iv 4 a ii b i c iv d iii O 1 02 3

3A 4A Read More Two coherent light sources P and Q are at a distance 3A from each other as shown in the figure The distance from Pon the x axis at which constructive interference may take place is y axis x axis and 4 out of is cor

Figure shows three concentric thin spherical shells A B and C of radii R 2R and 3R The shell B is earthed and A and C are given charges q and 2q respectively Find the charges appearing on all the surfaces of A B and C B C

2 Figure shows some energy levels of an atom If the transition E to E gives emission of ultraviolet radiatio which of the following transitions could give infra red radiation 13 1 E to E 3 E to E If the ga E 0 85 eV E 1 5 eV E 2 7 eV E 3 6 eV 2 E to E 4 E to E E Foundations in 017 A

In the circuit shown 1 and 2 are two ideal sources of unknown emfs Some currentsare shown in some branches of the circuit Potential difference across resistance 60 isVA VB 10V then 2 amp R 3 amp 452 452 81 17 252 82 www 352 3525 www 652

The time period of a simple pendulum is given by T 2 g measured value of the length of pendulum is 10 cm known to a 1 mm accuracy The time for 200 oscillations of the pendulum is found to be 100 second using a clock of 1 s resolution The percentage accuracy in the determination of g using this pendulum is x The value of x to the nearest integer is 1 2 2 3 3 5 4 4 The

A small ball of mass m starts its motion from height h as shown in figure undergoes head on elastic collision with stationary identical mass attached to end of string of length L The correct relation between h and L if mass m just complete the vertical circle about O h Om O Frictionless platform 5L 2 h h 2L 3L h 2 IL Om

A stone is projected from a balloon which is ascending with a velocity 1 m s The velocity of the stone w r t balloon is 3 2 m s at an angle of 45 with the horizontal as well as with the vertical upward direction Find the magnitude of velocity of stone with respect to ground

An oil drop of radius 2 mm with a density 3 g cm is held stationary under a constant electric field 3 55 105 V m in 3 the Millikan s oil drop experiment What is the number of excess electrons that the oil drop will possess consider g 9 81 m s 1 48 8 10 1 2 1 73 10 0 3 17 3 1010 X 4 1 73 10 2

A plane electromagnetic wave of frequency 100MHz is travelling in vacuum along the x direction At a particular point in space and time B 2 0 10 T where k is unit vector along z direction What is E at this point 1 0 6 V m 2 6 0kV m 3 6 0 V m 4 0 6kV m

3 36 The resistors 40002 and 80002 are connected in series with a 6 volt battery It is desired to measure the current in the circuit An ammeter of 10 ohms resistance is used for this purpose What will be the reading in the ammeter Similarly if a voltmeter of 10 00092 resistance is used to measure the potential difference across the 40002 resistor what will be the reading in the voltmeter

3 34 A potential difference of 220V is maintained across a 12000 rheostat as shown in figure 3 390 The voltmeter has a resistance of 6000 and point C is at one fourth of the distance from a to b What is the reading of voltmeter 220V b a Figure 3 390 1

What will be the average value of energy along one degree of freedom for an ideal gas in thermal equilibrium at a temperature T k is Boltzmann constant 1 KBT 2 KBT 3 KBT 4 KBT

vii A leaky parallel capacitor is filled completely with a material having dielectric constant K 5 and electrical conductivity o 7 4 x 10 22 m If the charge on the plate at the instant t 0 is q 8 85 C then calculate the leakage current at the instant t 12s 0 2 Al

22 1 12 second 2 8 second 3 15 second 4 10 second For the corresponding a t graph Draw the v t graph The particles starts from rest 1 2 3 2 K R 41 2 t t a 2 4 t Upuard represent positive and dou war

In the resistor network shown in the figure all the resistors are identical and each equal to 102 A current of 1A passes from terminal a to terminal b as shown in the figure The voltage between the terminals a and b is g R 10 1 4V

Example 1 Classify each of the following reactions as combination decomposition displacement or double displacement reactions i 2 KNO3 s 2 KNO s O g ii Zn s 2 AgNO3 aq Zn NO3 2 aq 2 Ag s iii Ni NO3 aq 2 NaOH aq Ni OH 2 NaNO3 aq iv Zn s 2 HCl aq ZnCl aq H g v 2 CuO s 2 Cu s O g vi Cl g 2 NaBr aq vii MgO s C s Br 2 NaCl aq CO g Mg s viii 2 KCIO3 2 KCl s 3 0 g ix CaQ s H O Ca OH aq

Conducting shell of radius R carrying charge Q another charge Q is placed at 3R distance from centre of shell If the potential at point P due to charge on 11 KQ Then the value of 20n is 3n R shell is 5 X X X X X X R X PAN X R 2 X X X 3R o