Physics Questions

2 What is a Rectifier Explain in detail two types of circuits for a full wave rectifier Also calculate rectifier efficiency and ripple factor for a full wave rectifier

Write down the relation between torque and angular momentum Write down the principle of conservation of angular momentum Define moment of inertia State the theorem of perpendicular axes Define Poisson s ratio What are its limiting values 2 1 1 2

m g a In the given figure a smooth parabolic wire track lies in the xy plane vertical The shape of track is defined by the quation yx Aring of mass m which can slide freely on the wire track is placed at the position A 1 1 The track is rotated with constant angular speed o such that there is no relative slipping between the ring and the track The walue of wo is

10 The coefficient of volume expansion of material of a metre scale is 18 x 105 K Find the fractional change in its length when temperature is changed by 20 C 1 36 x 104 A 2 18 x 104 3 12 x 10 4 4 6 x 104 13

1 4 2 3 Consider a long straight wire of cross section area A carrying a current i Let there be n free electrons per unit volume An observer places himself on a trolley moving in the direction opposite to the current with a speed v nAe and separated from the wire by a distance r The magnetic field seen by the observer is 2fr 2 zero 3 2 Tr Hoi TET a outer conductor carry equal currents in opposite directions 4

In the circuit in Figure 1 a 20 ohm resistor sits inside 114 g of pure water that is surrounded by insulating Styrofoam igure 20 0 Water 30 0 V 10 0 www 10 0 1 of 1 5 0 10 0 2 10 0 2 www ww 5 0 5 0 ww ww Part A If the water is initially at temperature 10 7 C how long will it take for its temperature to rise to 58 7 C Use 4190 J kg C as the specific heat of water and express your answer in seconds using three significant figures View Available Hint s At Submit VA O Request Answer S

In the figure shown a current I is established in the long straight wire AB Another wire CD carrying current I i placed in the plane of the paper The line joining the ends of this wire is perpendicular to the wire AB The resultant force on the wire CD is 1 zero towards positive y axis Bi K X C A 2 towards negative x axis 4 none of these

West A proton of mass m and charge q enters a magnetic field B with a velocity v at an angle with the direction of B radius of curvature the resulting path is MIV qB sin 0 qB B my qB sin 4 mv cos qB

A negative charged particle falling freely under gravity enters a region having uniform horizontal magnetic field pointing towards north The particle will be deflected towards 1 East 4 South 2 West A proton of mass m and charge a enters a magnetic field B with a velocity v at an angle 8 with the direction of B The 3 North

33 In the shown arrangement if f f and T be the frictional forces on 2 kg block 3kg block tension in the string respectively then their values are P 0 1 1N 2kg 1 2 N 6 N 3 2 N 2 2 N 6N ON 3kg 8N M 0 2 f 0 2 3 1 N6 N 2 N 4 data insufficient to calculate the required values

Proton Deuteron and alpha particle of same kinetic energy are moving in circular trajectories in a constant magnetic field The radii of proton deuteron and alpha particle are respectively rr and r Which one of the following relation AIEEE 2012 is correct 4 r r r 1 r r r C P 2 r r r 0 P 3 r r r

Rain pouring down at an angle a with the vertical has a speed of 10 ms A girl runs against the rain with a speed of 8 ms and sees that the rain makes an angle with the vertical then relation between a and B is

2 rd nd 1 mv m V 3 m m and v V 700 Two particles A and B of masses m and m respectively and having the same charge are moving in a plane A magnetic field exists perpendicular to this plane The speeds of the particles are v and v respectively and the trajectories are as shown in the figure Then X MALA mv m Va 4 m m and v VB

As raindrops fall in the air starting from rest a Its velocity and acceleration both increases b Its velocity increases and acceleration decreases c Both velocity and acceleration first increases then decreases d None of these

1 elec An electric current i enters and leaves a uniform circular wire of radius a through diametrically opposite points A charged particle q moving along the axis of the circular wire passes through its centre at speed u The magnetic force acting on the particle when it passes through the centre has a magnitude qvoi 2a 1 qv 12 quo 2ra 3 qv Hoi a zero

3 perpendicular to its velocity 4 zero A proton a deuteron and an a particle having the same kinetic energy are moving in circular trajectories in a constant magnetic field If rp ra and r denote respectively the radii of the trajectories of these particles then d T Tp r d Ta 3 I Id p r 4 r Id ra P 2 Ta rd p Two very long straight parallel wires carry steady currents I and I respectively The distance between the

1 1 2 3 273 A non planer loop of conducting wire carrying a current I is placed as shown in the figure Each of the straight sections of the loop is of length 2a The magnetic field due to this loop at the point P a 0 a points in the direction 1 k L 2a 2 j k i 3 i j k 1 85 7 SX100 fk i k B 4000X SY 100

Figure shows a circuit that contains three identical resistors with resistance R 9 0 Q each two identical inductors with induc tance L 2 0 mH each and an ideal battery with emf 18 V The current i through the battery just after the switch closed is 0000 a 0 2 A c 0 ampere R R L b 2 A d 2 mA NEET 2017

33 ment if f f and T be the In th frictional forces on 2 kg block 3kg block tension in the string respectively then their values are U 0 1 H 1N 2kg 3kg 8N N 0 2 1 2 N 6 N 3 2 N 2 2 N 6 N ON 3 1 N6 N 2 N 4 data insufficient to calculate the required f 011 er

A student measures the time period of 100 oscillations of a simple pendulum four times The data set is 90 s 91s 92 s and 95 s If the minimum division in the measuring clock is 1s then the reported mean time should be Choose only 1 answer A 92 2 s B 92 5 s C 92 1 8 s

1 700 N 2 1050 N A body is projected up a rough inclined plane from the bottom with some velocity It travels up the inclin and then returns back If the time of ascent is t and time of descent is t then 4 data insufficient 2 t t 3 t t 1 t t block of mass 9 1 kg is held against a wall by applying a horizontal force of 5N on the block If the co efficie of frictional force acting on the block is g

1 4 9 m s 2 9 8 m s 3 2 A body of mass 100 g is sliding from an inclined plane of inclination 30 What is the frictional force experienced if 1 7 Fr mgsing 0 1x 0x 101 5 1 7 N 1 5 21 7x N 13 17 5 N 1 7x 4 1 7 2 1 N 59 night horizontal road with a speed vo If the coefficient of friction between the tyres aned is

A concave mirror of focal length 20 cm is placed as shown in figure A circular disc of diameter 2 cm is placed on principal axis of mirror with its plane perpendicular to the principal axis at a distance 30 cm from the pole of mirror The radius of disc is increasing according to r 1 2t cm s then rate at which radius of image is changing Select an answer A B C 20 cm D 2 cm s increasing 4 cm s increasing 2 cm s decreasing 4 cm s decreasing

0 33 2 0 25 A block of mass 1 kg lies on a horizontal surface in a truck The coefficient of static friction between the bloc and the surface is 0 6 If the acceleration of the truck is 5 m s the frictional force acting on the block is 5 N 26 N 3 10 N 4 15 N A block of mass 2 kg rests on a rough inclined plane making an angle of 30 with the horizontal The coefficien The frictional force on the block is g 9 8m s 07

A block A kept on an inclined surface just begins to slide if the inclination is 30 The block is replaced by ar block B and it is found that it just begins to slide if the inclination is 40 1 mass of A mass of B 2 mass of A mass of B mass of B 3 mass of A 4 all the three are possible

Two block A and B placed on a plane surface as shown in the figure The mass of block A is 100 kg and that of block B is 200 kg Block A is tied to a stand and block B is pulled by a force F If the coefficient of friction between the surfaces of A and B is 0 2 and the coefficient of friction between B and the plane is 0 3 then for the motion of B the minimum value of F will be 1050 N A B 3 900 N 4 1100 N

1 4 Equal to the limiting force 3 scalar quantity A block is placed on a rough floor and a horizontal force F is applied on it The force of friction f by the floor on the block is measured for different values of F and a graph is plotted between them a The graph is a straight line of slope 45 b The graph is straight line parallel to the F axis e The graph is a straight line of slope 45 for small F and a straight line parallel to the F axis for large F There is small kink on the graph 1 c d 2 a d 3 a b a c lide if the inclination is 30 The block is replaced by another

In a coaxial straight cable the central conductor and the outer conductor carry equal currents in opposite directions The magnetic field is zero outside the cable 3 inside the outer conductor 2 inside the inner conductor 4 in between the two conductors

1 0 6 A block of metal is lying on the floor of a bus The maximum acceleration which can be given to the bus so that the block may remain at rest will be ug H 3 g 4 g g orizontal floor of the compartment of a train running along horizontal rails from left to 2

2 40 m 3 60 m 4 80 m The relation between time t and distance x is t ax bx where a and b are constants The acceleration is 1 2abv 2 2by 3 2av 4 2ay A car starting from rest accelerates at the rate f through a distance S then continues at constant speed for time t and

The coefficient of static friction between two surfaces depends on Nature of surfaces 2 The shape of the surfaces in contact 3 The area of contact 4 All of the above I

Four identical cells each of emf E and internal resistance r are to be used to deliver maximum power to a load of resistance Then the maximum power that can be delivered to the load is Select an answer A B C E 16 25 E 9 25 E2 r E 2r RO PAR

A particle is projected along a rough plane inclined at an angle of 45 with the horizontal if the coefficient of then the retardation is friction is g 1 2 2 2 802 0 1 G When a horizontal force of F newtons acts on it it

A body starts from rest and travels a distance S with uniform acceleration then moves uniformly a distance 2S an finally comes to rest after moving further 5S under uniform retardation The ratio of the average velocity to maximur velocity is 1 2 5 TI 2 3 5 3 4 7 4 5 7 FAIIMS 2018

A body is at rest at x 0 At t 0 it starts moving in the positive x direction with a constant acceleration At the same instant another body passes through x 0 moving in the positive x direction with a constant speed The position of the first body is given by x1 t after time t and that of second body by x2 t after the same time interval Which of the following graphs correctly describes x1 x2 as a function of time t AIEEE 2008 LL 1 x x 3 O x x LL 4 X X x x

Mark the correct statements about the friction between two bodies a static friction is always greater than the kinetic friction b coefficient of static friction is always greater than the coefficient of kinetic friction c limiting friction is always greater than the kinetic friction d limiting friction is never less than static friction 2 a b c b c d 3 a c d The coefficient of static friction between two surfaces depends on 4 a b d

Two cars leave one after the other and travel with an acceleration of 4 m s2 Two minutes after the departure of the first the distance between the car becomes 28 km The time interval between th departures of the cars is 1 190 sec 2 100 sec

A circular coil of n turns is wound on a wooden disc of radius a The disc is fixed rigidly to a light rod of length as shown figure The mass of the disc coil m A uniform magnetic field exists in the whole area of magnitude Bo in the horizonta direction If the coil carries current I per turn the angle which the rod will make with the vertical in equilibrium will be Select an answer A B C D 90 Cos sin Zero nia Bo mgl nia Bo mgl

5 A car is moving on a straight road The velocity the car varies with time as shown in the figure Initially at t 0 the car was at x 0 where x is position of the car at any time t Find acceleration of car at time t 15 sec and t 55 sec v m s 8 4 10 20 30 1 0 5 m s 2 3 0 0 4 m s 50 60 70 t sec 2 0 0 4 m s 4 0 0 2 m s

1 91 m 2 182 m 3 293 m 4 111 m A particle located at x 0 at time t 0 starts moving along the positive x direction with a velocity v that varies as v AIEEE 2006 a x The displacement of the particle varies with time as 1 2 1 1 t 2 3 1 4 t it of a particle is y y gt ft If its position is x 0 at t 0 then its displacement after unit time t 1 JAIEEE 2007

0 0 A charge Q is placed at one of the corner then flux passing through each non adjacent face to that corner Q will be 48 Two charge Q each placed at the face center then flux through cube will be Q 60 One charge is placed at edge of cube and other one Q at one of corner then net flux through cube will be O 8 Q 248 If only one Q charge is placed on corner then flux through each non adjacent face will be

a 3 b 2 c 6 d 3 2 A wooden piece floats half submerged in a tub of water If the system is transferred to a lift ascending with acceleration the wooden piece will c Remain half submerged d sink to the bottom a Sink a little more b Rise a little A tank is filled with water to height H A hole is made in one of the walls at depth D below the water surface

6 A square surface of side L metre is in the plane of the paper A uniform electric field E volt m also in the plane of the paper is limited only to the lower half of the square surface see associated with the surface is AIPMT Prelims 2006 DIVISION Educational Seguro The electric flux in Si units 1 EL 280 A 2 Me 2 3 Zero 4 EL2

on each other with their like 1 2s 2 2 3s 3 2 3 s The materials suitable for making electromagnets should have 1 high retentivity and high coercivity 2 low retentivity and low coercivity 4 low retentivity and high coercivity 3 high retentivity and low coercivity Two thin long parallel wires separated by a distance d carry a current of i A in the same direction They will i AIEEE 2004 LA JEFF 2005

city of a rocket with time The time of burning of fuel from the graph is v m s 1000 0 A 10 110 120 B 2 120 e t s 4 Data insufficient JAIIMS 200

A is fixed point at a height above a perfect inelastic smooth horizontal plane A light inextensible string of length has c end attached to A and other to a heavy particle The particle is held at the level of A with string just taut and released from rest The speed of ball just after striking the plane is A 2 3 Select an answer A B 1 4gl 3 2gl 3 gl 5

A fisherman hooks an old log of wood of weight 12 N and volume 1000 cm He pulls the log half way out of water The tension in the string at this instant is a 12 N b 8 N c 10 N d 7N When an incompressible liquid jet flowing in a pipe reaches a narrow cross section from a wider one its

A particle is thrown vectically up with an initial velocity 9 m s from the surface of earth take g 10 m s The time in s taken by the particle to reach a height of 4 m from the surface second time in seconds is 1 1 3 2 1 2 3 1 1 4 1 0 AIIMS 2018 Assertion Retardation is directly opposite to the velocity

1 R w 2x A charge Q is uniformly distributed over the surface of non condcting disc of radius R The disc rotates about an axis perpendicular to its plane and passing through its centre with an angular velocity o As a result of this rotation a magnetic field of induction B is obtained at the centre of the disc we keep both the amount of charge placed on the disc and its angular velocity to be constant and vary the radius of the disc then the variation of the magnetic induction at the centre of the disc will be represented by the figure AIEEE 2012

A bar magnet of magnetic moment M and moment of inetria I is freely suspended such that the magnetic axial line is in the direction of magnetic meridian If the magnet is displaced by a very small angle 0 angular acceleration is AIIMS 2018 magnetic induction of earth s horizontal field is B MB 0 I X4 MO 3 IB H 2 4 IB 0 M 10 MB in mubstance of susceptibility 3 x 10 is placed in a magnetising field of 4 x 10 Am Then the intensity AIIMS 2018