Basic Physics Questions and Answers

hind the value of A cobalt atomic no 27 target is bombarded with electrons and the wavelengths of its characteristic x ray spectrum are measured A second weak characteristic spectrum is also found due to an impurity in the target The wavelengths of the Klines are 225 0 pm cobalt and 100 0 pm impurity If atomic number of the impurity is Z 10X Find X take b 1

P114 A small positively charged ball of mass m is suspended by an insulating thread of negligible mass Another positively charged small ball is moved very slowly from a large distance until it is in the original position of the first ball As a result the first ball rises by h How much work has been done

A flow of 10 2 electrons per minute in a conducting wire constitutes a current of 1 6 x 10 7A 1 6 10 8 A 2 67 x 10 9 A 2 67 10 10 A

A wire of resistance 4 Q is stretched to twice of its original length The resistance of stretched wire would be 20 40 80 16 Q

approximately equals heat loss through terrestri radiation AIPMT Prelims 2005 1 66 North and South 2 22 North and South 1 2 3 40 North and South O 1

A block of mass m is placed at rest on an inclined plane of inclination to the horizontal If the coeffic of friction between the block and the plane is u then the total force the inclined plane exerts on the block 1 mg 2 mg cos 0 3 mg sin 0 4 mg tan 0

6 In free space a particle is projected from a point P on axis of a fixed rigid cone AOB at an angle a 37 with the axis see figure Distance of point P from the apex O is x 10 cm and the apex angle of the cone is p 20 All the collisions of the ball with the cone are perfectly elastic a Find the distance of closest approach of the ball from the apex b How many times will the ball collide with the cone B P a B

Alternate True False Right Wrong Yes No 1 Health of an individual depends on the surroundings 2 Gainful employment has no relation to individual health 3 On the basis of symptoms physicians look for signs of disease 4 High blood pressure is an infectious disease 5 Penicillin is effective against bacteria because it inhibits their wall fo 6 In open spaces air borne human diseases spread rapidly 7 AIDS spreads through sex blood to blood contact and from mothe 8 Personal hygiene is basic to prevent infectious diseases

The Fourier transform of f x is k dx e x x If x a x 8 x y 8 x where 8 x is the Dirac Delta function and prime denotes derivative what is f k a a i k iyk b a Bk yk c a i k yk d ia Bk iyk

vn all 07 3 56 The potential difference VA VB between points A and B for the circuit segment shown in figure 3 350 at the given instant is A 12V C 6V A 3A 6V 2 0 M 9 C 3Q ww 1 C Figure 3 350 B 12V fizog D 6V B SILLO

The position x of body changes with time t as shown in the graph The average speed by body in 10 s is x m 4 7 5 3 1 Zero 3 1 5 ms 1 2 4 Tot s 2 1 1 ms 1 4 0 7 ms 1

6 A L shaped uniform rod has both its sides of length 1 Mass of each side is m The rod is placed on a smooth horizontal surface with its side AB horizontal and side BC vertical It tumbles down from this unstable position and falls on the surface Find the speed with which end C of the rod hits the surface A B

43 USE CODE BAHUBALI FOR 10 OFF ON PLUS ICONIC SUBSCRIPTION Find Fmin minimum force required to pull the block D 1 umg 2 umg 2 4 3 Hmg 4 none of these T SIR

Two particles are projected simultaneously with the same speed u in the same vertical plane with angle 30 and 60 respectively with horizontal Then Ratio of their maximum heights is Ratio of their ranges is 1 13 Time when their velocities become parallel is U g 3 1 Time when their velocities become parallel is

Suppose that intensity of a laser is W m The rms electric field in units of V m associated with this source is close to the nearest integer is 8 86 10 12 C Nm c 3 108 ms mathongo mathong mathong athonge mathong

exponentially with distance x according to the relation I 1e where lo is the yana IIT Academy 13 07 21 OSR IIT CO SC ExPT 1 Q P attenuation in dB km for intensity at x 0 and a is the attenuation constant The an optical fibre in which the intensity falls by 50 percent over a distance of 50 km is A

41 A ray of light in air is incident on a glass plate at polarising angle of incidence It suffers a deviation of 22 on entering glass The angle of polarisation is a 0 b 68 c 56 of a flint glass block 6 d 90

7 A rod AB of length L having charge density a 2L x where x is distance from end A and a is a constant then electric field at point P will be A 1 Kal 3 KaL B 2 4 L Ka L Ka P

A person with normal vision using a compound microscope with fo 8mm and fe 2 5 cm is able to bring an object 9 mm from objective in sharp focus ONO The minimum tube length during adjustment is 9 7 cm with image at D The minimum tube length is 0 47 with angular magnification of eyepiece 10 The maximum tube length is 9 7 with angular magnification of eyepiece 11

A small bead of mass m is stationary with respect to rotating ring of radius R Angular speed of ring about a vertical diameter AA is w and distance of mass m from the line AA is r Then find the value of speed of bead am

18 An ideal monoatomic gas undergoes the process AB as shown in the figure If the heat supplied and the work done in the process are AQ and AW respectively The ratio AQ AW is v T YT A b 1 67 B c 1 25 T d 0 40

The following diagram is an arrangement to view the interference pattern produced by a wedge of liquid between a microscope slide and a glass block The interference pattern obtained is made of equally spaced parallel fringes The fringe separation or fringe width may be decreased by some of the following actions Consider one change at a time uniform monochromatic light microscope slide traveling microscope glass plate 43 to the incident light wedge of liquid glass block A By increasing the angle of the liquid wedge B By using a liquid of smaller refractive index C By using a thicker glass block D By using a longer liquid wedge of the same angle

A solid sphere of radius R is pulled by a force T acting at the top of the sphere as shown in the figure The sphere is in pure rolling Work done by the force when the centre of mass moves a distance d is T 1 Zero R 2 Td

An electron gun is emitting er at regular interval T with small speed v along line these are collected by a collector grounded at distance from gun and A is mid point of line joining gun collector collectie Gun 1 Consider a point P at line perpendicular to line of motion of e from point A such that PA t Now select CORRECT option s ift 2VT te is just equal to 2vT but f 2vT then max magnetic field due to moving electrons at P is B 14 D iff 2vT te t is just equal to 2v T but t2vT then min magnetic field due to moving electrons at P is B 0 ift 3vTie t is just equal to 3v1 but t 3vT then max magnetic field due to moving electrons at P is B 0 Iff 3vTie t is just equal to 3vT but t 3vT then min magnetic field due to moving electrons at P is Bmin 32 v 4913 2 Hoev 4x1 8 Ho ev 125 42 1 Hoev 4x 27 5 10 1 27 10 10 27 13 13

Given a 2 x 2 unitary matrix satisfying UU UU I with det U e one can construct a unitary matrix VV VV I with det V 1 from it by a Multiplying U by e ip 2 c Multiplying any row or column by e ip 2 b Multiplying a single element of U by e io d Multiplying U by e io

13 A body of mass 0 5 kg travels in a straight line with 1 velocity v ax 2 where a 5 m 2 s 1 The work done by the net force during its displacement from x 0 to x 2 m is 1 1 5 J 3 10 J 2 50 J 4 100 J

5 and a are three non zero non coplanar vectors with fixed magnitudes Angles between any of the vector with the normal of the plane containing other two is a Volume of parallelepiped formed by 5 and as co terminous edges is V and its surface area is S Which of the following is are true V cosa S 2 Vmax 5 5 16112 a 6 and 2 are equally inclined to each other If angle between is 9 then angle between a and plane of a

In case of a hydrogen like atom when an electron jumps from n 4 to n 3 it gives ultraviolet radiation The radiation of visible spectrum region may be obtained when transition of electron is from Only one correct answer A B C D n 4 ton 2 n 3 to n 2 n 5 ton 3 n 5 ton 4

Consider the reaction CO g H O 1 CO g H g Using standard absolute entropies at 298K calculate the entropy change for the system when 1 93 moles of CO g react at standard cond AS J K system

The forbidden energy gap in Ge is 0 72eV Given hc 12400 eV A The maximum wavelength of radiation that will generate an electron hole pair is approximately equal to hc 12400 eV A A 17222 A B 1722 A C 172220 A D 172 2 A

38 p V diagram of a cyclic process ABCA is as shown in figure Choose the correct statement AQA B negative b AUB C positive c AWCAB negative d All of the above PA B A C od Bare

A particle is released from the top of a tower of height 150m and another ball is thrown vertically upwards with velocity 20m s from a tower of height 50m at the same time Assume both are in a same vertical line Then time after which they collide to each other take g 10m s 1 2s 3 4s 2 3s 4 5s

In the following which of the statements is correct In YDSE and single slit diffraction sphere I wavefront is used 2 In YDSE plane wavefront and in single slit spherical wavefront are used 3 In YDS spherical wavefront and in single slit diffraction plane wavefront is used 4 In YDSE and single slit diffraction plane front is used

1 of a straight plane mirror His father is standing behind him as shown in the fig 3 Ma KH HI The height of the father is double the height of the child What is the minimum length of the mirror required so that the child can completely see his own image and his father s image in the mirror Given that the height of father is 2H H 2 3H notips intind 2 5H 6 4 1 Nano

Q 22 In the figure shown the velocity of lift is 2 m s while string is winding on the moto shaft with velocity 2 m s and block A i no Yomoving downwards with a velocity of 2 m the velocity of block B m s NEGA B 29041 ZIZZA 2 m s

Three boys are pushing horizontally a box placed on horizontal table One is pushing towards north with a 5 3 N force The second is pushing towards east and third pushes with a force 10 N such that the box is in equilibrium Find the magnitude of the force second boy is applying in newton

A point object is projected from a point on the principal axis of a concave mirror of focal length 20cm with speed of 5m s at an angle of tan 2 with principal axis as shown in fig Choose th correct option Consider the moment just after projection f 20cm A K30cm The magnitude of longitudinal magnification is 1 B Image speed is 5 2m s C Image velocity makes an angle 30 with principal axis Relative speed of image with respect to object is 61m s

32 A sound wave propagating along x axis in medium I of density p1 1 5 kg m is transmitted to a medium II of density p2 3kg m as shown X 400 P2 3 x 10 2 cos Medium I The equation of excess pressure developed by wave in medium I and that in medium II respectively are P 4 x 10 2 cos t X 1200 Incident sound wave Medium II in SI units PHYSICS in SI units If the intensity of transmitted wave is I2 wave in medium II and intensity of incident wave is I wave in medium I then find the value of 61 1

Q 24 A projectile is fixed at an angle 60 with horizontal Ratio of initial K E to K E when velocity vector of projectile makes an angle 15 with velocity of projection is

2 27 A parallel plate capacitor is maintained at a certain potential difference When a 3 mm thick slab is introduced between the plates in order to maintain the same potential difference the distance between the plates is increased by 2 4 mm The dielectric constant of slab is

A ray of light in incident on a plane mirror along the direction given by A 21 33 4k Find the unit vector along the reflected ray Take normal to mirror along the direction of B 31 63 2k a c 941 237j 68k 49 29 3 6 2k 7 b 941 683 237k 49 29 d None of these

A radio station has two channels One is AM at 1020 kHz and the other is FM at 89 5 MHz For good results you will use A longer antenna for the AM channel and shorter for the FM B Shorter antenna for the AM channel and longer for the FM C Same length antenna will work for both D Information given is not enough to say which one to use for which

Which of the following is not an example of a colloid A B C D and Dispersed phase medium both are solids Dispersed phase and medium both are liquids Dispersed phase medium both are gases and dispersion dispersion dispersion Dispersed phase is solid and dispersion medium is liquid

The whole wedge and block system is moving as shown in the figure Block of mass m is not slipping on the wedge Then which of the following statement is correct surface between M and mis rough M m a g tane 0 1 Work done by normal force on block is zero 2 Work done by friction force on block is zero 3 Work done by normal force on block is not zero 4 None of these

Angular part of a wave function is given as 15 X 0 0 sin 0 cos 20 Which of the following is correct for the given equatio 4 A Orbital has two angular nodes B Nodal planes are found in xy and yz planes orbital C Equation belongs to d 2 X D Equation represents 3d xy

2 g 2 3 g 3 4 g 4 The linear momentum of a particle is given by p a bt where t is time and a b are constants The for acting on the body varies directly as SAN 1 2 t 3 4

R R As shown in figure a spherical air lens of radii 10 cm is cut in a glass 1 5 cylinder Determine the focal length and nature of air lens If a liquid of refractive index 2 is filled in the lens find its focal length and nature H 1 5

2 23 Figure shows the graph of the x co ordinate of a particle going along the x axis as function of time Then the instantaneous speed of particle at t 12 5 s is m s 8 m 4 m 4 s 8 s 12 s 16 s B

Skipped Spring Moss System block of mass mhangs by means of a string which goes over a pullay of mass m and moment inertia I as shown in the diagram The string coas not sip relative to the puley Find the aquency of small oscillations M Osallations Simple Harmonic Motion 25 28 2 28

IR PHYSICS MOTION IN A STRAIGHT LINE 132 A train takes t sec to perform a journey if n 3 travel for t sec with uniform speed v n and finally it comes to rest with uniform retard ation Then average speed of train is 1 3n 2 V 2 2n 3