Basic Physics Questions and Answers

A hypothetical train moving with a speed of 0 6c passes by the platform of a small station without being slowed down The observers on the platform note that the length of the train is just equal to the length of the platform which is 200 m a Find the rest length of the train b Find the length of the platform as measured by the observers in the train

100 A particle moves in a plane along an elliptic path 2 given by x y At point 0 b the of velocity is u The y component of at this point is b u b d u a a x component acceleration a bu a c au b 2 b

b 2 and 3 respecti c 1 and 2 respectively d 1 and 3 respectively 2 A compass needle free to turn in a horizontal plane is placed at the centre of a circular coil of 30 turns and radius 12 cm The coil is in a vertical plane making an angle of 45 with the magnetic meridian when the current in the coil is 0 35 A the needle points west to east Determine the horizontal component of earth s magnetic field at the location a 3 9 x 10 tesla tesla b 3 9 x 105 tesla c 8 0 x 10 d 7 0 x 107 tesla current

Unstable pions are produced as a beam in a nuclear reaction experiment The pions leave the target at a speed of 0 995c The intensity of the beam reduces to half its original value as the beam travels a distance of 39 m Find the half life of pions a in the laboratory frame b in their rest frame

A screen is placed 50cm from a single slit which is illuminated with 6000 light If the distance between the first and third minima in the diffraction pattern is 3mm the width of the slit is Question Type Single Correct Type 1 0 1mm 2 0 2mm 3 0 3mm 4 0 4mm

The magnetic susceptibility of a paramagnetic material at 73 C is 0 0075 its value at 173 C will be a 0 0045 H c 0 015 b 0 0030 d 0 0075 i susceptibility of a paramagnetic b na c di d pa 90 The tem propert a I b C

m bility Xm magnetic 78 The range of magnetic susceptibility and relative magnetic permeability for diamagnetic substances are a 12x 0 05 1 1 X 0 02 1 b c 12 1 0 1 d 15 0 0 1 79 Out of given paramagnetic substance Calcium HAI arrang pieces a E b r c r d f 15 Mark

A mass attached to a string is swung ina a circular path with a uniform velocity about the horizontal plane as shown Seen directly from above which path would the mass most closely follow if the string breaks suddenly at T P 4Q 2 P R b Q R S c R d S

c 9 98 x 10 Am d 10 2 x 10 Am 68 A solenoid has core of a material with relative 77 A ba permeability 500 and its windings carry a current of 1 A The number of turns of the solenoid is 500 per metre The magnetization of the material is nearly a 2 5 x 10 Am c 2 0 x 10 A m b 2 5 x 10 Am d 2 0 x 10 Am liquid which a b d F 78 The ra

An object of mass my collides with another object of mass m2 which is at rest After the collision the objects move with equal speeds in opposite direction The ratio of the masses m2 m is hongo mathongo 1 3 1 2 2 thongmathongo mathongo 3 1 2 4 1 1 thongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathango

A wedge of mass 4 m lies on a smooth horizontal surface as shown in the figure The wedge has two men of masses m and 2m The system is initially at rest The man of mass 2m starts pulling the rope so that his acceleration with respect to wedge is 2a towards left The acceleration of m is a towards right with respect to wedge The string pulleys are massless and the coefficient of friction between each pulley string is and not sufficient to stop the slipping A The acceleration of the wedge is 3a 7 towards right B The magnitude of acceleration of m with respect to ground is 10a 7 C The tension in the string is throughout 10 ma 7 D The force exerted by both the men on the rope is same m 4 m 2 m

5 A man of mass 60 kg is pulling a mass M by an inextensible light rope passing through a smooth and massless pulley as shown in figure The coefficient of friction between the man and the ground is 1 2 The maximum value of M that can be pulled by the man without slip ping on the ground is 60 M approximately 1 51kg 2 26kg 3 46kg 4 32kg

these a Fature d f76 If a magnetic material is having magnet susceptibility x 1 then the relative magnetic permeability and type of magnetic material is a 0 diamagnetic c 1 paramagnetic b 2 ferromagnetic d 1 diama

2 An electric dipole consists of two electric charges of 1 0 C and 1 0 C separated by a distance of 2 0 cm The dipole is placed in an external electric field of 1 0 x 105 N C The maximum torque on the dipole is 1 0 2 x 10 3 Nm 2 1 0 x 10 3 Nm 3 2 0 x 10 Nm 4 4 0 x 10 Nm

xample 2 A uniform ladder of weight 100 N and length 6m is held in equilibrium by a horizontal forcel shown in the figure Using the method of virtual work find the value of force P The ladder ra 45 with the vertical

In a LR series circuit a sinusoidal voltage V V sincot is applied It is given that L 35mH R 112 V 220V 00 2x 50Hz and x 22 7 Find the amplitude of current in the steady state and obtain the phase difference between the current and the voltage Also plot the variation of current for one cycle on the given graph

The beam shown has an internal hinge at B A vertical load P 25 kN is applied at B Use L 2m Magnitude of the reactions i w forces and moments at A and C are L A B a Vertical reaction force at C is 12 5 kN vertical reaction force at A is 12 5 kN moment reaction at A is 0 kN m b Vertical reaction force at C is 0 KN vertical reaction force at A is 25 kN moment reaction at A is 50 kN m c Vertical reaction force at C is 25 kN vertical reaction force at A is 0 kN moment reaction at A is 50 kN m d Vertical reaction force at C is 0 kN vertical reaction force at A is 25 kN moment reaction at A is 25 kN m

a A sphere of radius R and linear dielectric material of dielectric constant carries a free charge density p r kr where k is a constant Determine the total energy of this configuration 2

In the figure shown there is non conducting disc of mass M 2kg and radius R 4 m On its upper lower parts of circumference Q and Q charge are uniformly attached such that liner charge density is The disc can freely rotate about a horizontal axis passing through O There is a uniform electric field E in the vertical direction such that QE mg If the disc is rotated by a small angle it performs S H M Its time period is given by T Q TR then p n is Take g O TELG 4 pr 22

57 A gas at a temperature 250 K is contained in a closed vessel If the gas is heated through 1 C the percentage increase in its pressure is B C D 0 4 0 6 0 8 1 0 AP R X100 100 H T

An aluminium wire of length 60 cm is joined to a steel wire of length 80 cm and stretched between two fixed supports The tension produces is 40 N Cross sectional area is 1 mm Steel and 3 mm aluminium Minimum frequency of the tuning fork which can produce standing waves with the joint as node is density of Al 2 6 g ce and density of steel 7 8 g cc Aluminium 60cm 1 90 Hz 2 145 Hz 3 180 Hz N Steel 80cm

An armoured car 2 m long and 3 m wide is moving at 13 m s when a bullet hits it in a direction making an angle tan 3 4 with the car as seen from the street The bullet enters one edge of the car at the corner and passes out at the diagonally opposite corner Neglecting and interaction between bullet and the car find the time for the bullet to cross the car

The Vernier scale of a Vernier caliper has 50 divisions coinciding with 45 divisions of main scale division If each main scale division is 1 mm then least count is 0 05 mm 0 45 mm 0 1 mm 0 2 mm

The displacement due to a wave moving in the positive x direction is given by y at time 1 0 and by y 1 at t 2s where x and y are in meters Velocity of the wave in m s is 1 1 2 0 5 3 2 4 4 14

A projectile is fired from ground level over level ground with an initial velocity that has a vertical component of 20m s and a horizontal component of 30m s Using g 10m s the distance from launching to landing points is A 40m B 60m C 80m D 120m

A rod a length I rotates with a small but uniform angular velocity o about its perpendicular bisector A uniform magnetic field B exists parallel to the axis of rotation The potential difference between the centre of the rod and n end is zero B 1 OB1 C B1 2 D Bol

The following curve represent rate of change of a variable y w r t x The change in the value of y as x changes from 0 to 11 is dyldx 20 1 60 3 35 0 36 2010 63 2 7 11 2 25 4 85 de 1x6x20 22

agnetism and K a 0 11 3 c 11 3 11 3 b 11 3 0 d 0 0 19 The dip angle at a location in southern India is about 18 Then the dip angle in Britain will be a greater than 18 c equal to 18 b lesser than 18 d zero 50 The angle of dip at a certain place where the horizontal and vertical components of the earth s magnetic field are equal is a 30 b 75 c 60 d 45 51 The vertical component of earth s magnetic field at a place is 3 times the horizontal component the value of angle of dip at this place is a 30 b 45 c 60 d 90 52 At a certain location in Africa compass points 12 west of geographic north The north tip of magnetic needle of a dip circle placed in the plane of magnetic meridian points 60 above the horizontal The horizontal component of earth s field is measured to be 0 16 G The magnitude of earth s field at the location is a 0 32 G c 4 2 G a tan 3 c tan 0 5 b 0 42 G d 3 2 G 53 Assume the dipole model for earth s magnetic field B which is given by the vertical component of Ho 2mcos8 and the horizontal magnetic field By 47 Ho msine 41 component of magnetic field By where 8 90 latitude as measured from magnetic equator then the loci of point for which dip angle is 45 b tan 2 d tan 1 b a motion of ions in earth s ionosphere motion of ions in earth s atmosphere motion of ions in earth s lithosphere motion of ions in the space b 0 90 d 90 0 c d 57 In the magnetic meridian of a certain place the horizontal component of earth s magnetic field is 0 25 G and dip angle is 60 The magnetic field of the earth at this location is a 0 50 G c 0 54 G 58 The equatorial magnetic field of earth is 0 4 G Then its dipole moment on equator is a 1 05 x 10 A m c 1 05 x 10 A m 54 The angles of dip at the poles and the equator respectively are a 30 60 c 45 90 b 0 52 G d 0 56 G 59 A compass needle whose magnetic moment is 60 A m pointing geographical north at a certain place where the horizontal component of earth s magnetic field is 40 x 10 Wb m experiences a torque of 1 2 x 103 N m The declination of the place is a 20 b 45 c 60 d 30 MAGNETISATION AND MAGNETIC INTENSITY 60 A magnetising field of 1500 A m produces flux of 2 4 x 10 weber in a iron bar of the cross sectional area of 0 5 cm The permeability of the iron bar is a 245 b 250 c 252 d 255 b 2 05 x 10 A m d 2 05 x 10 A m 55 At a given place on earth s surface the horizontal component of earths magnetic field is 2 10 T and resultant magnetic field is 4 x 105 T The angle of dip at this place is a 30 b 60 c 90 d 45 61 A solenoid has a core of a substance with relative permeability 600 What is the magnetic permeability of the given substance a 20m x 105 NA c 22m x 10 NA b 21mx 10 NA d 24 x 10 NA 62 A permanent magnet in the shape of a thin cylinder of length 50 cm has intensity of magnetisaton 10 A m The magnetisation current is a 5 x 10 A c 5 x 10 A b 6x 10 A d 6 x 10 A 63 A domain in ferromagnetic iron in the form of cu is having 5 x 100 atoms If the side length of t domain is 1 5 um and each atom has a dip moment of 8 x 1024 A m then magnetisation domain is a 11 8 10 A m b 1 18 x 10 Am c 11 8 x 10 A m d 1 18 x 10 Am 56 The earth s field departs from its dipole shape 64 A magnetising field of 2 x 10 A m produ substantially at large distance greater than about 3000 Km The responsible factor for this distortion is magnetic flux density of 8 x T in an iron roc relative permeability of the rod will be c 10 d 10 a 10 b 1

From a disc of mass M and radius R a circular hole of diameter R is cut whose rim passe through the centre The moment of inertia of the remaining part of the disc about perpendicula axis passing through the centre is 9MR2 A B 13MR2 32 32 C 11MR 32 D 7MR 32

of mass 2M is attached to a massless spring with spring constant k This block is connected to two other blocks of masses M and 2M using two massless pulleys and strings The accelerations of the blocks are a a2 and a3 as shown in the figure the system is released from rest with the spring in its unstretched state The maximum extension of the spring is xo Which of the following option s is are correct g is the acceleration due to gravity neglect friction A A a2 a a a3 B At an extension of Xo of the spring the 4 magnitude of acceleration of the block 3g 10 connected to the spring is C x 4Mg k to the spring is 3g oor M 2M 21 22 Laz D When spring achieves an extension of for the first time the speed of the block connected 2 2M

A heavy spherical ball of weight W rests in a V shaped trough whose sides are inclined at angle a and B to the horizontal Find the reaction on each side RE a P90 9 Rp WE 180 a B Ro 180 a B

ator 62 A permanent magnet in the shape of a thin cylinder of length 50 cm has intensity of magnetisaton 10 A m The magnetisation current is a 5 10 A 6x 10 A c 5 x 10 A 6x 10 A lomain in ferromagnetic iron in the form of cube b d

F 200 lb b Stanchion NOT F3 400 lb 30 TA D 3 For stanchion figure b if F 200j 150j 250k then direction angle y a is about 89 b is about half way between the positive x and positive y axes c cannot be determined without knowing the resultant orientation d must be 90 e None of the above

shipping the cylinder and the ground Find the time period of small oscillations of the system the cylinder and the plank and between 15 A circular spring of natural length lo is cut and welded with two beads of masses m and m such that the ratio of the lengths of the springs between the beads is 4 1 If the stiffness of the original spring is k find the frequency of oscillation of the beads in a smooth horizontal rigid tube Assume m m and m 3m 17 A rigid rod of mass m with a ball of mass M attached to the free end is restrained to oscillate in a vertical plane as shown in the figure Find the natural frequency of oscillation 16 A spring block pendulum is shown in the given figure The system is hanging in equilibrium A bullet of mass m 2 moving at a speed u hits the block from downward direction and get embedded in it Find the amplitude of oscillation of the block now Also find the time take by the block to reach its upper extreme position after hit by bullet 3 4L 14L M m m 18 In the arrangement as shown in the figure the sleeve mass M is fixed between two identical spring whose combined force constant is k The sleeve can slide without friction over a horizontal bar AB The arrangement rotates with a constant angular velocity about a vertical axis passing through the middle of the bar Find the period of small oscillations of the sleeve elle m eeeee 2m Natural length of spring 19 A uniform disc of mass M and radius R is connected two light springs 1 and 2 The springs are The other ends of the springs are rigidly doorov R C m A

The velocity of particle moving along the X axis varies with distance x as V 3x 5 At the insta of zero acceleration its velocity will be b 1 m sec a 0 m sec c 2 m sec d 3 m sec Ans a dr

The transverse displacement y x t of a wave on a string is given by v 2 t e This represents a 1 wave moving in x direction with speed 2 standing wave of frequency b 3 standing wave of frequency 4 wave moving in ty direction with speed A

2d 920 d 3 Two beads of equal mass m and unlike charges of modulus q and q2 can slide on a fixed frictionless non conducting rod bent at right angle Initially the beads are held at rest at distances d and 2d from the corner as shown and then released simultaneously When one of the beads reaches the corner where will the other bead be Treat the beads as particles

55 At a given place on earth s surface the horizontal component of earths magnetic field is 2 105 T and resultant magnetic field is 4 x 105 T The angle of dip at this place is a 30 b 60 c 90 d 45 56 The earth s field departs from its dipole shape

QA massive disc rotates about a vertical axis at an angular velocity A smaller disc of mass m and radius r whose axis is strictly vertical is lowered on the first disc The distance between the axes of the discs is d d r and the coefficient of friction between them is Determine the steady state angular velocity of the smaller disc What moment of force m must be applied to the axis of the larger disc to maintain its velocity of rotation constant The radius of the larger disc is R d r The friction at the axes of the discs should be neglected

7 Let the magnetic field on earth be modelled by that of a point magnetic dipole at the centre of earth The angle of dip at a point on the geographical equator is a always zero b positive negative or zero unbounded c d always negative

fJis the current density and d is a vector element of area then the integral J d over an rea represents the electric flux through the area 3 the average current density at the position of the area C the resistance of the area the resistivity of the area E the current through the area

136 The stress strain graph for this materials are shown figure assume scale is same for both graph a b c d Stress Ultimate Tension strength Linear limit Strain Material i E Fracting Point Stress Ultimate Tension strength Linear limit Strain Material ii Fracting Point Material ii is more elastic than material i and hence material ii is more brittle Material i ii have the same elasticity and the same brittleness Material ii is elastic over the larger region of strain as compared to i Material ii is more brittle than material i

f the potential difference across a resistor is doubled A only the current is doubled 3 only the current is halved C only the resistance is doubled O only the resistance is halved E both the current and resistance are doubled

Conduction electrons move to the right in a certain wire This indicates that A the current density an B the current density and electric field both point left C the current density points right and the electric field points left D the current density points left and the electric field points right E the current density points left but the direction of the electric field is unknown

Question No 21 A current of 4 A is maintained in a 20 Q resistor The amount of charge that flows through the resistor in one minute 0 50 L 240 C O 480 C 4C 898 14 881288 14 881288 14 881288 14 881288 14 881288 14 881288 14 881288 1 881280

Cleansing action of soap occurs because 1 Oil and grease can be absorbed into the hydrophobic centres of soap micelles and washed away 2 Oil and grease can be absorbed into hydrophilic centres of soap micelles acid washed away 3 Oil and grease can be absorbed into both hydrophilic and hydrophobic centres but not ched away

Q 20 4 For a first order reaction A Product the initial concentration of A is 0 1 M and after 40 minute it becomes 0 025 M Calculate the rate of O 00 18 reaction at reactant concentration of 0 01 M 3 47 x 10M min 1 O 3 47 10 M min

A lift starts from rest with constant upward acceleration It moves first 4 metre in 5 second A man in lift holds a packe of mass 2 kg by a string The tension in string during the motion is g 9 8 m s 16 5 N 20 2 N 15 7 N hr min 26 4 N

Copper contains 8 4 1028 free electrons m A copper wire of cross sectional area 7 4 10 7 m carries a current of 1 A The electron drift speed is approximately A 3 x 108 m s B 10 m s C 1 m s D 10 4 m s E 10 23 m s ep

13 12 Calculate the resistivity of an n type semiconductor from the following data density of conduction electrons 8x 10 cm density of holes 5 x 10 2 cm mobility of conduction electron 23 x 10 cm V s and mobility of holes 100 cm V 1 1 V s S