Physics Questions

57 In a circuit L C and R are connected in series with an alternating voltage source of frequency f The current leads the voltage by 45 The value of C is 1 1 2 3 4 2nf 2nfL R 1 nf 2nfL R 1 2nf 2nfL R 1 ca KE

An a particle accelerated through V volt is fired C towards a nucleus Its distance of closest approach is r If a proton accelerated through the same potential is fired towards the same nucleus the distance of closest approach of the proton will be 3 1 2 1 r 2 2 E XXL 44 Mx 4

A 4 pole d c shunt motor has a flux per pole of 0 04 Wb and the armature is lap wound with 720 conductors The shunt field resistance is 240 2 and the armature resistance is 0 2 2 Brush contact drop is 1V per brush Determine the speed of the machine when running a as a motor taking 60 A and b as a generator supplying 120 A The terminal voltage in each case is 480 V A 4 pole d c shunt motor has a wave wound armature with 65 slots each containing 6 conductors The flux por pola is 20 mWh and the has a resistance of 0 15

A wheel of mass M and radius r having charge Q uniformly distributed over its rim is rolling on rough horizontal ground without slipping about a light rod of length 2L A uniform magnetic field B directed opposite to the gravitational field is switched on in the space Find the value of mass m that should be placed at the end of rod to prevent the toppling of wheel 10 P CXO

8 The beam shown in the figure has negligible weight If the system hangs in equilibrium when W 400 N calculate the value of W Take sin 20 0 34 cos 20 0 94 0 7L 120 37 0 3L W 37 0 W

You have 10 23 carbon atoms Imagine that all the nuclei are put at north pole of the earth and electrons at the south pole of the earth radius 6400km The n force of attraction between the charg es approximately is A 5 10 5 N B 2 10 6 N C 13 6 10 3 N D 2 10 5 N

The work function of a substance is 4eV The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately 1 540 nm 2 400 nm 3 310 nm 0 220 pm

9 If the threshold wavelength for a metal is 6200 A then minimum energy required to eject an electron from the surface of metal is nearly 1 1 eV NCERT Pg 394 2 2 eV 4 08 eV

Two cylindrical tanks contain two different liquids with density in the ratio 2 1 Holes of cross section with ratio 2 1 are made at heights h and h below the liquid from bottom of the tanks Find the ratio when mass flux through holes is same h 16 1 8 1

A charge particle is projected with velocity v 41 31 m s in a region of space where uniform electric field 3 i 5 5 exist Motion of charge particle will be neglect gravity Circular O Helical O Parabolic V m and magnetic field B 81 61 Straight line

When a metallic surface is illuminated with light of wavelength the stopping potential is x volt When the same surface is illuminated by light of X 3 wavelength 22 the stopping potential is Threshold wavelength for the metallic surface is 1 42 m 3 61 2 42 4 8 3

The motion of a body of mass 2 kg is depicted graphically as shown in the given figure then the magnitude of net force acting on the body is A zero C 20 N B 2 N D 0 5 N Distance m 20 10

An air bubble in sphere having 4 cm diameter appears 1 cm from surface nearest to eye when looked along diameter If alg 1 5 the distance of bubble from refracting surface is Question Type Single Correct Type 1 2 3 4 1 2 cm 3 2 cm 2 8 cm 1 6 cm

A particle having charge q and mass m moving with velocity Venters a region of magnetic field B and electric field The motion of the particle will be Given V B and E are parallel Non uniform motion along a curved path Non uniform motion along a straight path O Uniform circular motion O Along a helix

President Duterte is driving his BMW motorcycle mass 980 kg and wants to accelerate from 18 m s to 32 m s is 7 seconds President Duterte is amazed of the power of his motorcycle What is the horsepower of it 47 hp 50 hp 77 hp

22 Two parallel conducting rails separated by a distance I are fixed on a plane surface inclined at an angle a to the horizontal as shown in figure Copper rod of mass m slides without friction on rails due to gravity A uniform vertical magnetic field exist throughout the region If at any instant velocity of rod is v the current through Ris 1 BA Bvl cos a R R www A 2 a ad Bvl tana R

2 Given that a photon of light of wavelength 10000 has energy 1 23 eV Now when light of intensity and wavelength 5000 falls on a photo cell the saturation current and stopping potential are 0 40 A and 1 36 V respectively The work function is 1 0 43 eV 2 1 10 eV 3 1 36 eV motallic plate 18

Two bodies A and B of masses 20 g and 15 g respectively are on a horizontal plane A is at rest and B is moving at 5 ns to the left B collides with A and as a result A starts moving at 3 m s to the left What is the final velocity of B 5

21 A uniform but time varying magnetic field B t exist in a circular region of radius R and is directed into the plane of the paper The magnitude of the induced electric field at distance r from the centre of the circular region varies as question paper 3 h Work E XX R XX B 1 X X xOx R X X X E E h h 1 2 R R X X X X XXX 4 XTX E R

A plastic rod of length 1 0 m carries uniform positive charge 4 0 C on half of its length and uniform negative charge 4 0 C on the remaining half of its length Find magnitude of it s net dipole moment in C m

11 An insulating rod of length 1 carries a charge q distributed uniformly on it The rod is pivoted at an end and is roated at a frequency f about a fixed perpendicular axis The magnetic moment of the system is 1 zero 2 qfl 3 nqfl 4 nqfl

esistance ed in it gnitude 0 lio d b 2 5 mJ O 1 coil of inductance L 50 H and resistance 0 52 is connected to a battery of emf 5 V A resistance of 100 is connected parallel to the coil Now at some instant the connection of the battery is switched off Then the amount of heat generated in the coil after switching off the battery is a 1 25mJ c 0 65 mJ d 0 12 mJ and F 0 present ABCDE a BL c 2E The se Cross as a L b d

A proton of charge e and mass m enters a uniform and constant magnetic field B B with an initial velocity V Vox Vor Which of the following will be correct at any later time t A x component of velocity of the proton will be V cos qBt m B y component of velocity will be Voy cos qBt m C z component of velocity will be Voy sin along direction qBt m D x component of velocity will remains unchanged

5 When photon of energy 3 8 eV falls on metallic surface of work function 2 8 eV then the kinetic energy of emitted electrons are 1 1 eV 3 0 to 1 eV 2 6 6 eV 4 2 8 eV

2 Figure shows two identical magnetic dipoles P and Q of magnetic moment M each placed at a separation 2d with their axes parallel to each other The magnetic field at midway M between the dipoles is Bo If one of them turned about centre by the magnetic field at M will be Assume short 2 bar magnets 1 3 S Bo 4 P 3Bo N 2d M 2 4 S 2 5B Q N

3 A circular coil is in y z plane with centre at origin The coil is carrying a constant current Assuming direction of magnetic field at x 25 cm to be positive direction of magnetic field which of the following graphs shows variation of magnetic field along x axis BA B a c Answer 0 BA B 0 x d b HONI 2R 3 b Direction of magnetic field at every point on axis of a current carrying coil remains same though magnitude varies Hence magnetic induction for whole the x axis will remain positive Therefore c and d are wrong Slope of the graph will be Magnitude of magnetic field will vary with x according to law Ho NIR 2 R x 3 2 Hence at x 0 B BA O dB dx O and when x B 0 3 NIR x 2 R x 5 2 It means at x 0 slope is equal to zero or tangent to the graph at x 0 must be parallel to x axis Hence b is correct and a is wrong Did you find it helpful

Will power not depend on the res stance of apparatus 27 An apparatus is connected to an ideal battery as shown in figure For what value of current power delivered to the apparatus will be maximum R 1 2 E 2R E 4R apparatus E 3 4 information is insufficient 25

nC m Let there be a non conducting infinite large sheet of charge of surface charge density 36T uncharged conducting spherical shell of radius 20 cm is placed in front of sheet A point charge 6mC placed at centre of the shell Force on point charge due to shell is x mN Find value of x

TO 45 O There exists a magnetic field in a cylindrical region of radius R The magnetic field is increasing at a constant rate a with respect to time The magnitude of induced electric field at a distance of from the axis of the cylindrical region will be 2 4 Mark for Review O ar hr min

A metal block of mass m slides on a horizontal surface which is lubricated with oil Assume that the initial velocity of the block is v at x 0 and a velocity dependent viscous resistance is working on the block given by F v kv 2 Show that the maximum distance travelled by the block is given by 2m v 1 2 k

71 A man stands on a frictionless horizontal ground He slides a 10 kg block on the surface with a speed of 3 m s relative the ground towards a vertical massive wall The wall itself it moving towards the man at a constant speed of 2 m s The block makes a perfectly head on elastic collision with the wall rebounds and reaches back to the man 3 second after the throw At the moment the block was thrown the wall was at a distance of 10 m from the man a Find the mass of the man b Find the ratio of work done by the man in throwing the block to the work done by the wall on the block

The true value of the angle of dip at a place is 0 If the plane of the dip circle is at 30 with the magnetic meridian the angle of dip is 0 Then one concludes that 1 0 0 2 0 0 3 0 0 4 0 0 30 h

The photoelectric work function 1 Is different for different materials 2 Is same for all metals 3 Depends upon frequency of the incident lig 4 Depends upon intensity of the incident ligh

Y An electron is to be accelerated from a velocity of 1 00x10 m s to a velocity of 7 50x10 m s Through what potential difference must the electron pass to accomplish this Vinitial Viinal Submit VAE 4 Part B Previous Answers Request Answer X Incorrect Try Again 9 attempts remaining V Thmunh what potential difference must the electron pass if it is to be slowed from 7 50x10 m s to a halt

The photoelectric threshold for a certain metal surface is 330 What is the maximum kinetic energy of the photoelectrons emitted if radiations of wavelength 1100 are used 1 1 eV 2 2 eV 3 7 5 eV 4 No electron is emitted

A triangular loop of side carries a current i It is placed in a magnetic field B such that the plane of the loop is parallel to magnetic field The torque on loop is Zero i B i B 4 3 i B

The wedge shown can slide without friction on a horizontal floor Mass of the wedge is M and its angle of inclination is 30 A block of mass m slides down the wedge without friction when released on its inclined face If path of the block relative to the ground makes an angle of 600 with the horizontal fin the ratio of mass of the block to that of the wedge m M M

While looking from the window you witness a squirrel moving with the speed of 18 m s on a horizontal ground The squirrel slides a distance of 18 m until it comes to a halt Considering the ground and the squirrel find the coefficient of friction 00 6 0 0 7 0 8 0 9

A particle starts from rest at t 0 and moves in a straight line with an acceleration as shown below The velocity of the particle at t 3 s is Kerala PET 2008 Acceleration m s a 2ms 1 1 c 6 ms e 1ms 1 4 2 4 TI 1 2 3 4 Time s b 4ms 1 d 8 ms 1

7 A tennis ball of mass 150 g is thrown towards a wall at a velocity of 10 m s It is hit back in the opposite direction with a velocity of 20 m s If the ball is in contact with the wall for a period of 0 01 sec then the magnitude of the force acting on the ball is A 500 N B 150 N C 450 N D 300 N

5 Two trains each of length 100 m moving in opposite directions along parallel lines meet each other with speeds of 50 km h and 40 km h If their accelerations are 30 cm s and 20 cm s respectively find the time they will take to pass each other

34 A charged particle moves along a circle under the action of possible constant electric and magnetic fields Which of the following are possible 1 E 0 B 0 2 E 0 B 0 3 E 0 B0 4 E 0 B 0 gh Work

A 90kg 120Kg 50 B 40Kg What is of Mr Incredible s feet so he stays in equilibrium a Determine the acceleration of the system if is less than your answer from 1 and 0 6 b Determine T and T c Verify Mr Incredible s acceleration using T and T

6 A box of mass 20 kg is sliding along the inclined plane which makes an 60 with the ground What is the magnitude of the Normal Force Assume g 10m s A 100 N B 173 2 N C 141 4 N D 200 N F N F F 4

a photoemissive cell with executing wavelength the fastest electron has speed v If the exciting wavelength is changed to 3 4 the speed of the fastest emitted electron will be da A v 3 4 2 B v 4 3 2 C Less than v 4 3 D Greater than v 4 3

A particle is moving on a straight line with a speed of about 0 5 m s To measure its speed points are marked on the line of motion which are exactly separated by 5 mm To have an accuracy of 99 in the determination of speed the minimum least count of the measuring clock is nx 10 4 s Find value of n

Find the velocity and the position as functions of the time for a particle of mass m which starts from rest subject to the following force function F x Fosinct where Fo and c are positive constants 12 5 2 51

A cell is connected between the points A and C of a circular conductor ABCD of same material with centre at O If B and B2 are the magnitude of magnetic field at O due to current in ABC and ADC respectively then B B ratio 5 6 2 is B 60 D

The bob of a pendulum is 0 2 kg It is hung by mean of 1 2 m string from the ceiling If it is pulled horizontally and make a distance of 0 3 m from the ceiling what will be its velocity at the lowest point when released 4 2 m s 5 2 m s 1 0 m s 11 2 m s

A 100 ohm resistor is connected in series with a 4 H inductor The voltage across resistor is Vo 2 sin 1900 The voltage across inductor is 1 60 sm 1000 t x 2 2 8 sin 1000 2 3 80 sin 1000 2 4 6 sin 1000 t 2