Physics Questions

1 A photoelectron is moving with a maximum velocity of 106 m s Given e 1 6 x 10 9 c and m 9 1 x 10 1 kg the stopping potential is 1 2 5 V 3 2 0 V 2 2 8 V 4 1 4 V

A man travelling in car with a maximum constant speed of 20 m s watches the friend start off at a distance 100 m ahead on a motor cycle with constant acceleration a The maximum value of a for which the man in the car can reach his friend is A 2 m s B 1 m s 100 m C 4 m s D None of these

In the given where a 1 NC hypothetical closed surface is taken as shown in figure y 0 0 0 b Ey Eof Ex d x i X The total charge enclosed within the close surface is

The acceleration due to gravity on a planet A is 9 times the acceleration due to gravity on planet B A man jumps to a height of 2 m on the surface of A What is the height of jump by the same person on the planet B 1 2 9 m 3 6 m 2 18 m 4 2 3 m

An airplane pilot wants to fly from city A to city B which is 1000 km due north of city A The speed of the plane in still air is 500 km hr The pilot neglects the effect of the wind and directs his plane due north and 2 hours later find himself 300 km due north east of city B The wind velocity is B 106 km hr at 45 N of E D 106 km hr at 45 N of W A 150 km hr at 45 N of E C 150 km he at 45 N of W

Electrostatics has Statement 1 and Statement 2 Of the four choices given after the statements choose the one that best describes the two statements An insulating solid sphere of radius R has a uniformaly positive charge density p As a result of this AIEEE 2012 uniform charge distribution there is a finite value of electric potential at the centre of the sphere at the surface of the sphre and also at a point out side the sphere The electric potential at infinity is zero Statement 1 When a charge q is taken from the centre to the surface of the sphere its potential qp energy changes by 3 0 pr 3 0 Statement 2 The electric field at a distance r r R from the centre of the sphere is 1 Statement 1 is true Statement 2 is true and Statement 2 is the correct explanation of Statement 1 2 Statement 1 is true Statement 2 is true and Statement 2 is not the correct explanation of statement 1 3 Statement 1 is true Statement 2 is false 4 Statement 1 is false Statement 2 is true

27 In the circuit shown the ratio 1 1 is equal to 1 1 1 2 2 1 3 4 3 3 4 3 4 2 5 5 V 10 CI 1 39 80 32 T 2 V 202

Is it possible a Yes b No c Cannot be predicted d Insufficient data to reply 10 A D 15 A 5 A

46 ww W ww E r you R If E 6V r 20 then maximum power dissipa through R is 1 18 W 2 9 W 3 36 W 4 3

If the radius of the earth be increased to a factor of 5 then by what factor its density be reduced to keep the value of the acceleration due to gravity on the surface same 1 3 1 25 1 55 est 5 JAY 5

A B C D Column I Particles are projected at same speed from same point on level ground such that their range is same Particles are projected from same point on ground such that maximum height reached is same Particles are projected horizontally from same point at a height with different initial velocities Particle are projected from the same point at a height with same initial speed direction of velocity makes equal angle with horizontal one below and the other above horizontal Column II P Q R S Time of flight will be same Speed just before reaching ground will be same Vertical component of velocity just before reaching ground will be same Minimum kinetic energy durir the flight will be equal

The velocities of A and B are marked in the figure Find the velocity of block C assume that the pulleys are ideal and string inextensible Tim s A O B

In an undershot water wheel the cross sectional area a 0 1 m of the stream is striking the series of radial flat vanes of the wheel The velocity of stream is 6 m s The velocity of vanes is 3 m s If the power supplied by jet in watts is 2700K find K Water jet U

Three boys are running on a equitriangular track with the A same speed 5 ms At start they were at the three corners with velocity along indicated directions The velocity of approach of any one of them towards another at t 10 s equals 1 7 5 ms B 2 10 ms 4 0 ms 100 m 60 60 100 m 100 m 60 C

Two long conductors are arranged as shown above to form overlapping cylinders each of radius r whose centers are separated by a distance d Current of density J flows into the plane of the page along the shaded part of one conductor and an equal current flows out of the plane of the page along the shaded portion of the other as shown What are the magnitude and direction of the magnetic field at point A blow norusis HeimVacuum Conductor L el inlog omsa od nave A 2 dJ in the y direction B H 2r d r in the y direction D 2 Jr d in the y direction

18 v t graph for a particle is as V m s shown The distance travelled in the first 4s is a 12 m b 16 m c 20 m d 24 m 8 t sec

A metal rod OA of mass m length r is kept rotating with a constant angular speed o in a vertical plane about a horizontal axis at the end O The free end A is arranged to slide without friction along a fixed conducting circular ring in the same plane as that of rotation A uniform constant magnetic induction B is applied perpendicular into the plane of rotation as shown in figure An inductor L and an external resistance R are connected through a switch S between the point O a point C on the ring to form an electrical circuit Neglect the resistance of the ring and the rod Initially the switch is open a What is the induced emf across the terminals of the switch b i Obtain an expression for the current as a function of time after switch S is closed S R ii Obtain the time dependence of the torque required to maintain b the constant angular speed given that the rod OA was along the positive X axis at t 0 X X mmmm L X y 20 0 AXX

A triangular pulse is moving with speed 2 cm s along a rope kept along x axis whose one end is free at x 0 as shown in the figure Choose the correct option regarding this pulse A B 2cm 0 5cm 2cm x 0 at t 1 sec C Particle speed at t 0 sec is 1 cm s 1cm 2cm X C 2cm 1cm 1cm 2cm x 0 at t 1 sec D Particle speed at t 0 sec is 2 m s

c A voltmeter should have small resistance d A voltmeter should have large resistance 8 A capacitor of capacitance 500 uF is connected to a battery through a 10 k2 resistor The charge stored on the capacitor in the first 5 s is larger than the charge stored in the next a 5 s b 50 s c 500 s d 500 s 9 A capacitor C of capacitance 1 F and a capacitor C of capacitance 2 F are separately charged by a common battery for a long time The two capacitors are then H separately discharged through equal resistors Both the discharge circuits are connected at t 0 a The current in each of the two discharging circuits is zero at t 0 b The currents in the two discharging circuits at t 0 are equal but not zero c The currents in the two discharging circuits at t 0 are unequal d C loses 50 of its initial charge sooner than C loses 50 of its initial charge

18 A subatomic particle of mass 10 ug is in thermal equilibrium with its surrounding at a temperature of 400 K Then the wave length of this particle will be

If a point charge is placed is front of a grounded conducting sphere the induced charges on the surface of the sphere is non uniform To calculate the force on Q due to this sphere or electric field at any point on surface of sphere or outside it an image charge must be kept on the line joining centre of sphere and Q To find this image charge and its position we make the potential due to Q and image charge together on any two points on the surface of sphere equal to ZERO Once these value are obtained force on conductor due to Q will be equal to force between image charge and Q Also field at any point on the sphere or outside will be equal to net field due to Q and image charge Now answer the following questions 9 Force between the sphere and Q is equal to Q Rd 4 Eo d R 2Q Rd A C En 2R d R B P Q Rd 4 Eo 2R d 2 Q Rd 4 R 20 D Image charge d 4

b What is the resistance in the following network between A and B A ww 192 192 www 19 B

The equivalent capacity of the infinite net work shown in the figure across AB is Capacity of each capacitor is 1 F D AH BH HE E H 1 2 1uF 3 HH HH 3 2 1 F 4 2 1 3 1 UF

XXX A block of mass m placed on a horizontal conveyor belt is attached at None end of a spring of force constant k The other end of the spring is attached to a support A Coefficients of static and kinetic friction between the belt and the block are s and k sk Initially the belt the block and the support all are moving towards the right with constant velocity u and the spring is relaxed The support is suddenly stopped a Explain qualitatively the mechanism of motion of the block after the support is stopped b Find the maximum and minimum deformations of the spring c Find period T of the oscillatory motion of the block g T 2 x ks kk 1 tant A MK 9 2 MS MK g ANSWERS A xamin k 12 60 x 1 14 15mg 2 2 Enerzy b w mg 2 x m Remix kxmax 2 14 mg x max 2 mg x lex mu 2 1xmax Mk mg CMS MR mg Muz R

A 4 F capacitor is connected to another 8 F capacitor The combination charged to 300 V calculate 1 Total charge on the combination Total energy stored in the combination

21 Determine the values of currents I I2 and 13 in the network shown in Fig 2 85 Given that R R 222 R3 122 R4 R5 42 E 5 V and E 10 V Ans I I3 1 875 A I 2 5 A E SE I1 I A www www B R4 11 12 13 WWW R R3 www R 13 11 www R5 Fig 2 85 E 2 12 13 12 13

25 A particle of mass 10g moves along a circle of radius 6 4 cm with a constant tangential acceleration What is the magnitude of this acceleration if the kinetic en ergy of the particle becomes equal to 8 10 J by the end of the second revolution after the beginning of the motion 1 0 18 m s 3 0 1 m s 2 0 2 m s 4 0 15 m s

Find acceleration of block in given figure 1 6 m s 3 1 m s 10kg 3750 N 37 2 11 m s 4 10 m s

6 Two balls of equal mass are projected from a tower simultaneously with equal speeds One at angle 8 above the horizontal and the other at the same angle 0 below the horizontal The path of the centre of mass of the two balls is a a vertical straight line b a horizontal straight line d a straight line at angle a 0 with horizontal da parabola

path XY as shown The abcd is a coil adjacent to the path of electron What will be the direction of current if any induced in the coil X b a C electron d Y Re AIPMT 2015 1 No current induced 2 abcd 3 adcb 4 The current will reverse its direction as the electron goes past the coil Dolhi 110005 Ph 011 47623456

2 An object moves with velocity V 1 towards the inclined plane mirror as shown in figure The velocity of the image is A Vi B V C 3i 2 2 1 D 1 V 3 Y Iv 30 x i

A disc of radius r and carrying positive charge q is rotating with an angular speed o in a uniform magnetic field B about a fixed axis as shown in figure such that angle made by axis of disc with magnetic field is 0 Torque applied by axis on the disc is A C qor Bsin 0 2 qor Bsin 0 clockwise Disc Fixed axis dio u B anticlockwise D B qor Bsin 0 482 qor Bsin 0 A 3 anticlockwise clockwise bhulungna sil to

The lens shown is equiconvex having refractive Index 1 5 In the situation shown the final image of object coincides with the object The region between lens and mirror is now filled with a liquid of Rrefractive Index 2 Then find the separation between O image formed by convex mirror f 20 cm A 33 cm 30 cm HH B 66 cm 20 cm C 16 cm D 32 cm

3 At what height above the earth s surface would the acceleration due to gravity be i half ii one fourth of its value at the earth s surface Radius of earth 6400 km Ans i 2650 km ii 6400 km

There are 5 different boxes and 7 different balls The number of ways in which these balls can be distributed so that box 2 and box 4 contain 1 ball each and at least 1 box is empty is N The order of putting the balls in the boxes is not considered The digit in the hundredth s place of N is equal to

he following table has 3 columns and 4 rows Based on table there are THREE questions Each uestion has FOUR options A B C and D ONLY ONE of these four options is correct 1 A ball of mass m moving with velocity vo in m Vo horizontal direction collides with a stationary ball of mass m line of impact makes an angle e with horizontal choose the correct option 1 11 III Column 1 Masses m m m m m m 3m 2m 3 1 m m m IV m m m 3m Column 2 Coefficient of restitution e 0 0 ii iii e 2 1 e T 3 iv For 8 0 which of the following is true A 1000 0 e 1 Column 3 Angle between final velocities of two balls P Q R S B P A zero r 2 r 3

Surface charge density o E I 2 II I Area A Surface charge density o FIGURE 2 25 The parallel plate capacitor 74 the plates is disc the area of each plate and d the separation between them The two plates have charges and 9 Since d is much smaller than the linear dimension of the plates d A we can use the result on electric field by an infinite plane sheet of uniform surface charge density Section 1 15 Plate 1 has surface charge density o 9 A and plate 2 has a surface charge density o Using Eq 1 33 the electric field in different regions is Outer region I region above the plate 1 E O 280 O 280 0 2 39

and the block is 0 25 and that between the hand and the block is 0 15 what force must he exert Ans 5 kg wt A man lifts a 16 kg can of oil by pressing his two hands towards each other against the rough sides If the co efficient of static friction is 0 25 what force must he apply with each hand Ans 32 kg wt A man weighs 70 kg What is the greatest weight he can pull along a horizontal floor by a horizontal mp

8 A long cylindrical shell carries positive surface charge o in the upper half and negative surface charge o in the lower half The electric field lines around the cylinder will look like figure given in figures are schematic and not drawn to scale JEE Main 2015 1 3 2 4

Which of the following quantities remains constant during projectile motion A Average velocity between two points B Average speed between two points C dv dt d dt v D 1 only A 3 A and C 2 only C 4 C and D

28 Three large plates A B and C are placed parallel to each other and charges are given as shown The charge that appears on the left surface of plate B is 42 30 3C 4C 5C 5L

Example 3 73 An aircraft flies at 400 km h in still air A wind of 200 2 km h is blowing from the south The pilot wishes to travel from A to a point B north east of A Find the direction he must steer and time of his journey if AB 1000 km

down a frictionless hemispherical bowl It passes the point A at t 0 At this instant of time C the horizontal components of its velocity are v A bea Q of the same mass as P is ejected from A att 0 alon the horizontal string AB with the speed v Frictio between the bead and the string may be neglected Le tp and to be the respective time taken by P and Q reach the point B Then fe tp ta c tp tq b tp tQ d p length of arc ACB D

1 A projectile is projected from ground such that 2 second before it reaches the highest point it makes an angle 37 with vertical then the velocity of projectile at highest point is 1 5 m s 2 10 m s A 20 m s

3 The distance of the moon from the earth is about 60 times the radius of the earth What will be diameter of the earth approximately in degrees as seen from the moon a 1 b 2 c 4 d 6

In a p n junction diode change in temperature due to heating a does not affect resistance of p n junctio b affects only forward resistance c affects only reverse resistance d affects the overall V characteristics of p n junction

15 The figure represents the observed intensit of X rays emitted by an X ray tube as function of wavelength The sharp peaks and B denote Intensity A B Wavelength a white radiations b characteristic radiations band spectrum 12 centinous spectrum

5 A bar magnet is 10 cm long is kept with its north N pole pointing north A neutral point is formed at a distance of 15 cm from each pole Given the horizontal component of earth s field is 0 4 Gauss the pole strength of the magnet is a 9 A m c 27 A m b 6 75 A m d 1 35 A m 152

A potentiometer wire of length L and resistance 102 is connected in series with a battery of e m f 2 5V and a resistance in its primary circuit The null point corresponding to a cell of e m f IV is L obtained at a distance If the resistance in the primary circuit is doubled then the position of new 2 null point will be

12 The average electromagnetic 1 EH value of poynting vector in wave is 2 4 E Ho 2 E Ho