Physics Questions

Draw the circuit diagram of a half wave rectifier Explain its working What is the frequency of ripple in its output Why do we need filters in a power supply

Example 9 5The earth takes 24 h to rotate once about its axis Ho much time does the sun take to shift by 1 when viewed fro the earth Solution Time taken for 360 shift 24 h Time taken for 1 shift 24 360 h 4 min

An electron moves along vertical line and towards observer the pattern of concentric circular field lines of magnetic field which is produced due to its motion 1 ACW In horizontal plane 3 CW In horizontal plane 16 12 2 ACW In vertical plane 4 CW In vertical plane

1 AB is an inclined plane of inclination 30 with horizontal Point O is 20 m above point A A particle is projected horizontally from O leftwards and it collides with the plane AB perpendicularly Speed of the particle at the time of projection should be g 10 m s O a 13 m s c 4 5 m s B 30 A 20 m b 8 3 m s d 2 3 m s

Two identical small plastic balls are rubbed against a piece of wool such that both of them received approximately 2 10 2 and 2 5 x 10 2 electrons respectively Now both the charged balls are kept at a distance of 25 cm in air Calculate the nature and magnitude of force between both the balls

In the circuit shown the cells A and B have negligible resistances For V 12 V R 500 S and R 100 2 the galvanometer G shows no deflection The value of V is a 4V c 12 V VA R VB T b 2V d 6V

Paragraph for question nos 14 Katrina and Kareena were crossing a river which is flowing towards right at constant speed 5 m min travelling in two different boats having same speed in still water They have taken photographs of the river banks at t 0 t T t 2T times Bo Co are two trees on other bank of river Distance shown in diagram are in m T 1 min Photograph taken by Katrina Bo t 0C B t TC Box t 2T Co 10 3 5 303 Bo 15 3 15 3 Photograph taken by Kareena t 0 0 Co Bo 10 3 t t Con B O 5 31 t 2T Co O 14 Mark correct option b Katrina s boat has crossed the river in minimum time and Kareena s boat has crossed the river along the shortest path b Kareena s boat has crossed the river in minimum time and Katrina s boat has crossed the river along the shortest path c Kareena s Boat as well as Katrina s boat has crossed in the minimum time d None of these 15 What is the distance between B and C a 10 m b 30 3 c 30 m d None of these 16 Mark the correct option a Velocity of boat in still water will be 10 m min b Velocity of boat in still water will be 10 3 m min

In given circuit applied voltage V 50 2 sin 100m volt and mmeter reading is 2A then calculate value of

A cell can be balanced against 110 cm and 100 cm of potentiometer wire respectively with and without being short circuited through a resistance of 10 Q2 Its internal resistance is a 2 0 ohm c 1 0 ohm b zero d 0 5 ohm

A body moving at 2 m s can be stopped over a distance x If its kinetic energy is doubled how long go before coming to rest if the retarding force remains unchanged A x B 2x C 4x A block weighing 10 N t D 8x

8 A body is moving with uniform velocity of 8 ms When the body just crossed another body the second one starts and moves with uniform acceleration of 4 ms 2 The time after which two bodies meet will be a 2 s b 4 s c 6s d 8 s

In the adjacent figure a light and thin string is wound on a uniform disc of mass m and radius r very tightly The disc is kept at rest in vertical position on a rough horizontal surface and string passes over a fixed pulley A light pan is attached to the free end of the string The maximum mass that can be placed on the pan so that disc will not slip s equal to mK 2 Find K coefficient of friction between the surface nd the disc is 0 1 and there is no friction between string and pulley disc

3 Two cliff of heights 120m and 100 4m are separated by a horizontal distance of 16m I a car has to reach from the first cliff to the second the horizontal velocity of the ca should be 1 16 ms 1 3 2 ms 1 2 4 ms 1 4 8 mg 1

In Young s experiment the width of the fringes obtained with light of wavelength 6000 A is 2 0 mm What will be the fringe width if the entire apparatus is immersed in a liquid of refractive index 4 3

The distance of final image from AB as observed by observer P is A object Air O 20cm BE H 2 Air H 4cm 2cm H3 1 5 6cm P 1 2

A monochromatic light of frequency v is incident on isolated metallic sphere of radius r The threshold frequency is vo vo v Find the number of photoelectrons emitted before the emission of photoelectrons will stop

Find the mass Mf of the hanging block in figure 5 E16 which will prevent the smaller block from slipping over the triangular block All the surfaces are frictionless and the strings and the pulleys are light 8 34 Find the acceleration of the blocks A and B in the three situations shown in figure 5 E17 A 4 kg 5 kg A B A 4 M 2 ko Figure 5 E16 A 29 Figure 5 E17 13 Joga 305 kg 1 b 3 100 g 50 g 30 Figure 5 E18 1 kg 500 g 291 3 35 Find the acceleration of the 500 g block in figure 5 E18 P A 09 c 2 kg K 36 A monkey of mass 15 kg is climbing on a rope with one end fixed to the ceiling If it wishes to go up with an acceleration of 1 m s how much force should it apply to the rope If the rope is 5 m long and the monkey starts from rest how much time will it take to reach the ceiling 165 TOS A monkey is climbing on a rope that goes over a smooth light pulley and supports a block of equal mass at the other end figure 5 E19 Show that whatever force the monkey exerts on the rope the monkey and the block Slo move initially both were change as time passes Figure 5 E19 The monkey B shown in figure 5 E20 is holding the tail of the monkey A which is climbing up The masses of the monkeys A and B are 5 kg a respectively If A can tolerate a tension of 30 tail what force should it apply on the rope in carry the monkey B with it Take g 10 m s 70N 100N Figure 5 E20 1 c 7 d 13 a 2 8 14 1 b d 4 a c 7 c d 1 10 N 39 Figure 5 E21 shows a man of mass 60 kg stand 2 3 1 10 a light weighing machine kept in a box of mass The box is hanging from a pulley fixed to the a 3 1 1 10 through a light rope the other end of which is h 4 5 N and the man himself If the man manages to keep th at rest what is the weight shown by the machine force should he exert on the rope to get his correct 6 0 25 Na 5 F 2 on the machine the mo m 7 F 1 777

In the shown circuit the rms current through source i will be A 4A C 5A B 15 A D 7A i L L 0 125H ic C 1 4mF R R 12 5Q

126 For amongst the following curves which one shows the variation of velocity with time t for small sized spherical body falling vertically in a long column of viscous liquids 1 V4 1 3 2 4 V4 VA

2 There is a small air bubble inside a glass sphere u 1 5 of radius 10 cm The bubble is 4 cm below surface and is viewed normally from the outside as shown in figure Find the apparent depth of the bub H 1 0 H 1 5

On the horizontal surface of a truck a block of mass 1 kg is placed 0 6 and truck is moving with acceleration 5 m s then the frictional force on block will be A 5N B 6N C 5 88N D 8N

23 Two particles are executing SHM on two parallel straight lines Amplitude A and time period T of both the particles are equal At time t particle is at displacement x A and other at 0 one A and they are approaching towards each X 2 other Time after which they will cross each other is 1 3 2 T 3 5T 6 4 T 6

The young s modulus of material of a thin ring shaped elastic body is Y The mass of ring is m area of cross section is A its initial radius is R Ring is a little elongated then left alone At what time will ring circumference be same as it was initially Neglect loss of energy 1 3 2 TMR 8YA mR YA 2 4 3 2 mR YA KmR V2YA

67 If coefficient of friction between all surfaces is 0 4 then find the minimum force F to have equilibrium of the system Take g 10 ms a 62 5 N c 135 N Wall 25 kg VI 15 kg F b 150 N d 50 N

A plane mirror 50 cm long is hung on a vertical wall of a room with its lower edge 50 cm above the ground A man stands infront of the mirror at a distance 2 m away from the mirror If his eyes are at a height 1 8 m above the ground then the length distance between the extreme points of the visible X 26 region perpendicular to the mirror of the floor visible to him due to reflection from the mirror is Find the value of x m

Example 3 6 A battery of 10 V and negligible internal resistance is connected across the diagonally opposite corners of a cubical network consisting of 12 resistors each of resistance 1 2 Fig 3 23 Determine the equivalent resistance of the network and the current along each edge of the cube A A A I 2 D 1 2 1 2 D 1 2 I B 1 2 B 31 C 1 2 C

100 ml A metallic sphere of density 5 g cm 3 is pro jected upward from the bottom of a pond with a velocity 10 m s The velocity of the sphere on reaching the surface of the water is found to be 8 m s Determine the pressure exerted by water at the bottom of the pond Neglect the viscous force acting on the sphere T M

86 A B C D battery Two identical capacitors are connected in series and the combination is connected with a shown Some changes in the capacitor 1 are now made independently after the steady state is achieve listed in column I Some effects which may occur in new steady state due to these changes on the capacitor 2 are listed in column II Match the changes in capacitor 1 in column I with corresponding effect on capacitor 2 in column II Column I A dielectric slab is inserted Cap 1 Cap 2 P Separation between plates increased 9 A metal plate is inserted connecting both R plates The left plate is grounded S Column II Charge on the capacitor increases Charge on the capacitor decreases Energy stored in the capacitor increase pollets festasie No change is occurred

2 During the first 18 min of a 60 min trip a car has an average speed of 11 ms What should be the average speed for remaining 42 min so that car is having an average speed of 21 ms for the entire trip a 25 3 ms c 31 ms 1 b 29 2 ms 1 d 35 6 ms 1

0 A ring is made of a wire having a resistance R 12 22 Find the points A and B as shown in the figure at which a current carrying conductor should be connected so that the resistance R of the sub 8 circuit between these points is equal to 3 4 5 128 c 4 3 a b d 4 1 12 3 1 2 41 O 12

Which of the following set up can be used to verify law wwwww www www wwwww wwww A A b A d www www A 2003 2M H

A cord passing over a pulley connects two masses as shown where m 3 10 kg and m 6 00 kg The system accelerates with a magnitude of 0 97 m s2 The coefficient of kinetic friction between the masses and the incline is the same for both masses Assume the pulley is frictionless and the cord is massless Due to the nature of this problem do not use rounded intermediate values in your calculations including answers submitted in WebAssign m 35 0 m 35 0 a What is the coefficient of kinetic friction b What is the tension in N in the cord N

A current passes through a resistor Let K and K represent the average kinetic energy of the conduction electrons and the metal ions respectively a K K c K K b K K d Any of these three may occur

26 kJ 2 2 12 kJ 3 4 18 kJ 4 1 05 kJ 100 Which of the following is intensive property of a 540 cal g thermodynamic system 1 P and T 3 V and P 101 Work dono in tent heat of 2 V and T 4 V and E

xample 4 12 a A current carrying circular loop lies on a smooth horizontal plane Can a uniform magnetic field be set up in such a manner that the loop turns around itself i e turns about the vertical axis b A current carrying circular loop is located in a uniform external magnetic field If the loop is free to turn what is its orientation of stable equilibrium Show that in this orientation the flux of the total field external field field produced by the loop is maximum c Aloop of irregular shape carrying current is located in an external magnetic field If the wire is flexible why does it change to a circular shape

Example 3 58 A man A moves due to East with velocity 6 ms 1 and another man B moves in N 30 E with 6 ms 1 Find the velocity of B w r t A

A body of mass 2 kg is lying on a rough inclined plane of inclination 30 Find the magnitude of the force parallel to the incline needed to make the block move a up the incline b down the incline Coefficient of static friction 0 2 7 Repeat part a of problem 6 if the push is applied horizontally and not parallel to the incline

List I contains different AC circuits with rms voltage of ac sources as shown List II contains the mms currents supplied by the ac voltage sources Then match the options of List I corresponding correctly with the options of List II LIST I LIST II P R S wwwww X Xc 4Q 100 V X www Xc 30 R 80 www 120 V 18888000 X 562 Xc 30 50 V www X 8Q Xc 40 100 V ww R 30 wwww R 80 ww R 802 www R 30 6 26 yo 4 37 to 1 2 3 4 I 25 A Ims 5 A Im 10 5 A Im 20 A

c Must every magnetic configuration have a north pole and a south pole What about the field due to a toroid d Two identical looking iron bars A and B are given one of which is definitely known to be magnetised We do not know which one How would one ascertain whether or not both are magnetised If only one is magnetised how does one ascertain which one Use nothing else but the bars A and B

17 A train is moving with a velocity of 30 km h 1 due East and a car is moving with a velocity of 40 km h due North What is the velocity of car as appears to a passenger in the train

The linear density of a vibrating string is 1 5x10 kg m The equation of a transverse wave along the string is given by y 0 02 2x 60t where x y are in m and t in s The tension in the string is

vi In sonometer if tensions and length both becomes four times taking mass per unit length consta then for vibration of same frequency Tunning fork Number of loop will becomes

1 A positively charged particle projected towards east is deflected towards north by a magnetic field The field may be a towards west c upward b towards south d downward horizontal circle on

49 System of Particles and Rotational Motion 34 Four rods of mass M and length are joined at the centre Find the moment of inertia of the system about axis of rotation AA shown here M12 3 4M12 1 A 2 90 M1 12 15M

Two blocks of mass M 20kg and M 12kg ar connected by a metal rod of mass 8 kg The system is pulled vertically up by applying a force of 480 N as shown in figure The tension at the mid point of the rod is IFF 1 0010 480 N M Mo

A In the circuit shown the cells A and B have negligible resistances For V 12 V R 500 S and R 100 2 the galvanometer G shows no deflection The value of V B R a 4V c 12 V is VB b 2V d 6V

50 0 kg of N g and 10 0 kg of H g are mixed to produce NH3 g Calculate the moles of NH g formed Identify the limiting reagent in the production of NH3 in this situation Hint N g 3H g 2NH3 g to form water Find out the mass of water obtained Which

4 An electric field of magnitude 1000 N C is produced between two parallel plates having a separation of 20 cm as shown in figure 29 E4 a What is the potential difference between the plates b With what minimum speed should an electron be projected from the lower plate in the direction of the field so that it may reach the upper plate c Suppose the electron is projected from the lower plate with the speed calculated in part b The direction of projection makes an angle of 60 with the field Find the maximum height reached by the electron E T 2 cm

from rest when spring was in its natural length The pulley also has mass m but it is frictionless Suppose the value of m is such that finally it is just able to lift block M up after releasing it Column I i ii Tension in the rod when m is in equilibrium iii Weight of m required to just lift M iv Normal force acting on M when m is in equilibrium Tension in the string when displacement of m is maximum possible a b C d M Column II M 3 8 2 Mg 00 8 Knu 2 2 mg oooooo Ro Str

2 28 Two fixed identical conducting plates o and B each of are charged to Q and q respectively where Q q 0 A third identical plate y free to move is located on the other side of the plate with charge q at a distance d figure The third plate is released and collides with the plate B Assume the collision is elastic and the time of collision is sufficient to redistribute charge amongst B and y YA a B Y TdA q Q a Find the electric field acting on the plate y before collision b Find the charges on and y after the collision c Find the velocity of the plate y after the collision and at a distance d th