Physics Questions

25 In a gas discharge tube if 3 x 1018 electrons are flowing pe sec from left to right and 2 x 10 8 protons are flowing p second from right to left through a given cross section Th magnitude and direction of current through the cross sectic a 0 48 left to right b 0 48 A right to left c 0 80A left to right d 0 80 A right to left

8 a Name the type of radiation which when enters the muscle tissues produces heat b Name the type of radiation that is used in communication using cellphones c Which among the following radiation has a lower frequency Violet light Red light

mig is If the centre of the mass of three particles is at rest and it is known that two of them are moving along different non collinear lines then the third particles must also be moving If the centre of mass of a system remains at rest then the net work done by all the forces acting on the system must zero If the speed of centre of mass of a system remains zero then the net external force acting on the system must be zero If the speed of centre of mass is changing then there must be some work being done by the internal forces on the system

iv Deduce the moment of inertia for a hollow spherical shell about an axis passing through its centre Also deduce the moment of inertia of the same shell if the axis of rotation is passing through one of its tangents 6 4 10

4 When two resistances X and Y are put in the left hand and right hand gaps in a wheatstone meter bridge the null point is at 60cm If X is shunted by a resistance equal to half of itself then find the shift in the null point a 26 7 cm b 36 7 cm c 46 7 cm d 96 7 cm

A solid sphere of mass m 2 kg gravity s 0 5 is held stationary relative to tank filled with water by attaching a string between sphere and bottom of the tank The tank is accelerated upward with acceleration 2 m s2 The tension in the string is p 1000 J15 24 N 2m b a my kg 2 4 N m a 2 m s

39 River of width 500 m is flowing at a speed of 10 m s A swimmer can swim at a speed of 10 m s in still water If he starts swimming at an angle of 120 with flow direction then the distance it travels along the river while crossing the river is i elbihaq 9 6 to to bear 1 250 m grit zasl ed 2 500 3 m 289 500 3 3 m avar viool opsteve 4 500 m 14 qat

The magnetic force acting on a charged particle having charge 2 C in a magnetic field of 2 T acting in y direction moving with velocity 21 3 x 10 m s is 4 N in Z direction 8 N in y direction 8 N in Z direction 8 N in z direction

A Non inverting Op Amp has input resitance of 6 6 K Ohm and feed back resistance of 68 K Ohm If the input voltage is 0 7 What is the output voltage of Op Amp 101924461 NOTELO

Consider Fraunhoffer diffraction pattern obtained with a single slit illuminated at normal incidence At the angular position of the first diffraction minimum the phase difference in radius between the wavelets from the opposite edges of the slit is A 4 C 2 B 1 2 D T 1995

5 A cyclist and a motorcyclist are moving with speed V and 2V as shown The separation between them initially is L The sped of both the vehicle is constant Find out the time in which the motorcyclist will overtake the cyclist A 2L V C L V B 3L V D None 2V D ondent to the frame of references forences toment is not true in case of relative motion D

232 If t represents the install instantaneous velocity becomes perpendicular the direction of initial velocity during a projectile to represents the time after which the partic attains maximum height then t t is 1 2 2 6 1 g 2u g u an ad lisw mori eonslab A 16W

6 Select the correct relation between speed of sound in a and elasticity of air 1 Speedo adiabatic elasticity of air 2 Speed adiabatic elasticity of air 3 Speed isothermal elasticity of air 4 Speed isothermal elasticity of air X x

For a series R L C Network is shown determine the un damped natural frequency and damping ratio of the circuit 6v S 10 5 rad sec 0 25 10 5 rad sec 0 5 10 4 rad sec 0 5 10 4 rad sec 0 25 1kQ 10mH 0 01

4 One end of a uniform wire of length L and of Wo is attached rigidly to a point in the roof and a weight W is suspended from its lower end If S is the area of cross section of the wire the stress in the wire at a height L 4 from its lower end is 1 W S 2 W 2 W W 4 S 3 W 3W 4 S 4 W W S

Q 11 Two coherent send waves sources of different intensities which interfere The ratio of maximum intensity to the minimum intensity is 25 The intensities of the sources are in the ratio 1 25 1 3 9 4 2 5 1 4 625 1

94 A particle started revolving from rest with a constant angular acceleration a in a circular path of radius r If centripetal acceleration becomes numerically equal to tangential acceleration at time t then t is equal to POW 1 t 3 1 a 1 fhow 1 2 t 2250 5 a tese TE 2 0 C 4 t 010 4

A 4V B 4 A swimmer starts swimming upstream and he travels L distance with respect to earth in a given time If the swimmer starts moving down the stream with same speed with respect to river then find out the distance covered by the swimmer in the same time as in the upstream The speed of river flow is V and that of the swimmer is 2V with respect to river A L B 2L C 3L D None

C L V D 6 Which statement is not true in case of relative motion A Relative displacement is independent to the frame of references B Relative separation is independent to the frame of references C Relative velocity is independent to the frame of references D Time is independent to the frame of references

Heat is being supplied at a constant rate to a sphere of ice which is melting at the rate of 0 1 gm sec It melts completely in 100 sec The rate of rise of temperature thereafter will be Assume no loss of heat 0 8 C sec 2 5 4 C sec 3 3 6 C sec 4 will change with time 1

0 b a d 1 5 V decrease the range of an ammeter its resistance need to be increased An ammeter has resistance R and range I Which of the following resistance can be connected in series with it to decrease its range to R n R n 1 Ro n 1 None of these n electric bulbs are connected one by one across rence V At that time power con respectively Now if series CO

Given 1 47E0 9 x 10 Nm C Q6 What is electrostatic shielding Explain one application of it Q7 A potential difference of 4 Volt is applied across a copper wire of length 4 m Calculate potential gradient along the wire 2 2 2

26 A swimmer can swim in still water at a speed of 5 m s and takes t and to time to cross a river in shortest time and shortest path respectively If the speed of river increases then time taken to cross the river in shortest time and shortest path be and to respectively Then ES 0 OSS 1 4 t t 1 2 t t t 1 000 8 to spns ne pri am 4 t t t to 3 t t to sta t

213 A vector A which has magnitude 8 0 is added to a vector B which lies on x axis The sum of these two vectors lies on y axis and has a magnitude twice of the magnitude of B The magnitude of vector B 213 is 1 8 enslqntigrovom albine 3 2 2x8 Honce 8 noitalen gni 4 8 5 wav B 218 The for e each o to rit to F is r ilan bo est oppos 1 Be

229 If A and B are two vectors inclined to each other at angle 0 then component of A perpendicular to B and lying in the plane containing A and B is A S A B A B low 61 tete1 ts prin Berit no vising 2 A Bsmi Bioge narw Jis B teg erit to Toge en ap to elons 4 A B 901002 nge prinio prit ofT allow orl diw 3 A R

3 4 m s 12 A man can row a boat with 8 km h in still water He is crossing a river of width 8 km where the speed of water flow is 4 km h What direction should he head the boat to cross the river in shortest time 1 30 with the current 2 60 with the current 3 90 with the current 4 120 with the current

3 HQ 3 Hp riw 33 A body is projected with same speed at different angles covers the same horizontal distance R If T and T are two time of flights then R is equal to 1 gT T 1 2 2 or 97 A 2 2 gT T alm Evor 8 10 OWT 8S 2 mei numril es 3 T T o isto 4 2gTT26902

The reading of voltmeter in the circuit shown is 6 V 1 2 25 V 2 3 25 V 40 2 wwww 60 2 www V 40 Q 3 4 25 V 4 6

Let a vector ai B be obtained by rotating the vector 31 by an angle 45 about the origin in counterclockwise direction in the first quadrant Then the area of triangle having vertices a 3 0 and 0 0 is equal to 1 3 2 1 4 2 2

80 A point is moving on X Y plane such that y co ordinates varies with time as x a sin wt y a 1 cos wt where a and w are positive constants Velocity of the particle is mie a 1 aw 2 2 aw 3 810 3 aw 4

The combination of straight and the circular wire carrying current i is shown in the figure It consists of a circular arc of radius R and central angle made by the arc is radians and two straight sections whose extensions intersect at the centre C of the arc The magnetic field that the current carrying wires produce at point C is O B Hoi 8 R R out of the plane of the figure OB o out of the plane of the figure SR

An electron and a particle enter a region of uniform magnetic field of induction B with equal velocities The direction of magnetic field B is perpendicular and into the plane of the paper and the velocity of the given particles is upwards as shown in figure by the arrow Then qualitatively identify the direction of paths of electron and the a particle O I for a particle III for electron I for a particle Il for electron OI for electron Il for a particle O I for electron Ill for a particle 4

Q 4 How much work is done to move a charge of 0 05 C between two points on a certain equipotential surface 1 Q 5 The electro static force of 0 2 Newton acts on a small sphere of charge 2 x 10 C due to another sphere of charge 9 x 106 C Calculate the distance between the spheres Given 1 4780 9 x 10 Nm C 2

What amount of heat must be supplied to 2 0 10 2 kg of nitrogen at room temperature to raise its temperature by 45 C at constant pressure Molecular mass of N 28g R 8 3J mol K and Cp for N 7 2R 2 1 1033 55 J 2 933 75 J

a State and prove Gauss theorem of electrostatics Using this find the electric field near a uniformly charged plane sheet b If the intensity of the electric field near the earth s surface is 330 V m directed downwards calculate the surface density of charge on the earth s surface

3 450 MJ m 25 A uniform wire of length 3m and mass 10 kg is suspended vertically from one end and loaded at other end by a block of mass 10 kg The radius of cross section of wire is 0 1 m The stress in the middle of wire is g 10 m s 1 1 4 x 104 N m 2 4 8 x 103 N m 3 96 104 N m 4 35 10 N m

The value of the potential difference across a conductor is 28 V A current of 7 A is passing through it What is the conductance of the given conductor O 0 259 O 0 759 O 0 50 O 19

the figure a 5cm and b 20cm If the M I of th wheel is 3200kg m the angular acceleration would be 12X1 6 0 1 10 1 rad s 3 10 3 rad s 12 N 30 10N 9N LFL s d 2 10 rad s 4 10 4 rad s d

72 Two projectiles are thrown horizontally from a high cliff in opposite direction with same speed 20 m s simultaneously At what time velocities of both particles become perpendicular 1 2 2 s 2 2 s 3 4 s 4 4 2s E

A V 3 A river is flowing with speed V When the swimmer is swimming upstream then his speed is 2V with respect to earth Find out the speed of the swimmer if he starts swimming downstream with same speed with respect to river A 4V B 3V C 2V D None instream and he travels L distance with respect to earth came speed with ith

In the arrangement shown in figure the mass of the rod M exceeds the mass m of the ball The ball has an opening permitting it to slide along the thread with some friction The mass of the pulley and the friction in its axle are negligible At the initial moment the ball was located opposite the lower end of the rod When set free both bodies began moving with constant accelerations Find the friction force between the ball and the thread if t seconds after the beginning of motion the ball got opposite the upper end of the rod The rod length equals l I

10 A semicircular glass tube filled with water containing an air bubble is sealed at its ends If the tube is held with its plane vertical and made to move in its plane with a constant acceleration the bubble stays aside of the highest point as shown in the figure What can you conclude about acceleration vector of the tube a It points towards the left c Its magnitude is g tan0 b It points towards the right d Its magnitude is gcot 0 Fluid Mechanics Vertical 0 Centre 7 5

190 In the given diagram shown for a projectile what is the angle of projection 10y4 VA 1 tan 1 3 tan 1 4 3 D Dela al nozieq A pos on to boited or br p nt leups al 20 m 30 m 18 10m 5 al ekinsq ed 2 tan X w 180d a wo is evoll 4 tan 813 12878 WoT NEM A 802 5 3

27 Three bulbs of 40 W 60 W and 100 W are arranged in series with 220 V Which bulb has minimum resistance 1 100 W 3 60 W 2 40 W 4 Equal in all bulbs Hint Resistance doesn t depend on external voltage or series parallel connection Larger the power lower the resistance

3 53 225 An object is moving on a circular path of with constant speed v The average acceleration of the object after it has travelled three and half rounds is to adi 1 3 2v Tur 4v 7 ont 9 2 4 4v 3 r moos8 E 2v 7 fr

assumed to be perfectly conducting 30 69 E A wwww 62 www B 302 TEU 7 Statement 1 The current in branch AB is non zero Statement 2 The potential difference between A and B is non zero Choose the correct option 1 Statement 1 is correct but Statement 2 incorrect 2 Statement 2 is correct but Statement 1 incorrect 3 Both statement are correct

76 A man wants to cross a river 600 m wide flowing at 8 m s in shortest time Man has a speed of 6 m s in still water What is the path length covered by man in the river 154 1 Infinite Rp binne 3 100 m 2 1 km 1 4 1000 cm

153 Two stones are thrown simultaneously from the top of a building horizontally but in opposite directions they will be moving perpendicular to each other initial say after time t then t is equal to speed of stones are u and u respectively and acceleration due to gravity is g 1 3 U U g 4142 2 2 4 U 4 V g 20142 2 a

D 7 A train is moving with speed V as shown It crosses a station which has the length 2L as shown The length of the train is L Find out the time in which the train will cross the station A 2L V C L V B 3L V D none V 2L with respect to river is

In the figure there are two particles A B each of mass m A is connected to ceiling by a light inextensible thread OA and E is connected to A by a light inextensible thread AB Initially B is vertically below O and the strings are taut as shown If the system is released from rest immediately after the release tan 37 3 4 O 1379 B A