Basic Physics Questions and Answers

The position x of a particle moving along x tast x 3 where axis varies with time all quantities are in Sl units The displacement in m of the particle in time duration t 0 to t 5 s is 11 x k find value of k

Two identical point particles A and B are placed in front of concave mirror of focal length 20 cm at distances 10 cm and 30 cm respectively The particles oscillate perpendicular to the principal axis such that the displacement equation for both the particles is given by YA YB 0 1 sin nt cm Find the maximum separation between the images of A and B measured perpendicular to the principal axis in mm Correct answer 04 00

A circular loop of radius R carries current and is parallel to the x y plane A uniform magnetic field is switched on such that tension in the loop becomes To Force exerted by right half of the loop on the left half is lo O Na TO O2To H

The half value period of a radioactive element is 20 seconds At any instant the number of radioactive nuclei is one million Ten seconds later the number of radioactive nuclei left are O 106 2 106 S O 5 10 2 5 105

A cubical block is on a rough fixed incline pla angle of inclination 0 What is the shift in normal reaction from the center of the cubical block if block is at just rest 1 6 2 4 0 m 2 a tane D

The small particle of mass m is given an initial high velocity in the horizontal plane and winds its cord around the fixed vertical shaft of radius 1 m All motion occurs essentially in the horizontal plane If the angular velocity of the cord is 0 8 rad s when the distance from the particle to the tangency point is 5 m then determine the anglar velocity w in rad s of the cord after it has turned through an angle 1 rad 10 Correct answer 1 00 O O

A glass vessel of volume V is to be partially filled with a liquid of volume coefficient of expansion 7 so that the space inside the vessel may remain constant at all temperature If the coefficient of linear expansion of glass is a the volume of the liquid required for the purpose is O O Yv a 2av Y

For the circuit shown angular frequency wo is adjusted so that current 1 through source is in phase with applied voltage source Then 3 ooo m R www CV R Vo 1 R LC 21

0 For a solid liquid interface the following equation is applicable YsV YSL YLV cos 0 where 0 is the contact angle YSV YSL and YLV are the surface tension of soli interfacial tension of S L and surface tension of liquid If a metal pan has to be made non sticking for cooking appliance A Edible surfactants are to be added to the cooking water B The metal has to be coated with high energy substance C The metal has to be coated with a low energy substance D Edible surfactants that can adsorb at S L interface can be added

A wedge ABC of mass M can slide freely on a smooth fixed plane DE inclined a an angle On face AB of the wedge there is a small block of mass m What is acceleration of wedge ABC with respect to ground in m s M 2kg m 4kg g 10 m s E B m 60 M B 30 D

53 Work done in moving a unit positive test charge from infinity to a point inside an electric field is called 1 electric potential 3 field intensity 4 potential difference 2 field 54 In India AC changes its direction after every

24 The resultant of two vectors A and B is perpendicular to A and it has magnitude half that of B The angle between the vector A and B is A 90 B 120 C 140 D 150 25 A piece of wood of mass M and volume V is floating in water Which of the following is true A Volume of displaced water is V B Mass of displaced water is M C Density of water is M V D Density of water is less than M V

Two resistors of resistance R and 3R have thermal coefficients of resistance a and 2a respectively Equivalent thermal coefficient of resistance for the combination connected in parallel is 5 4 5 3 7a 5 7

kg and m 20 kg are connected by a light string and are placed on a horizontal rought surface If a force of 300 N is applied on m 2 in the horizontal direction on either of these blocks Then each block gains accelration of 1 m s If friction force are equal on both block then find force of friction and tension m J T T m F

atalyst Package for NEET A uniform rod AB of length and mass m is free to rotate vertically about a fixed point A The rod is released from rest in the horizontal position The initial angular acceleration of the rod will be 3 A 3g 21 g 21 2g 2 31 A A 3g 40 B

A temperature in the range of 40 C to 55 C is to be measured with a resolution of 0 1 C The minimum number of ADC bits required to get a matching dynamic range of the temperature sensor is 1 8 2 10 3 12

A cylindrical copper wire of a finite length is melted and recasted in form of a wire of rectangul cross section of the same length Choose the correct statement from the following 1 The resistivity of the wire remains unchanged 2 The resistance of the wire changes 3 Both the resistance and the resistivity of the wire change 4 Volume of the wire changes

1 Which of the following temperatures is the highest A 220 F B 80 C C Boiling point of water D 273 K

9 Two rings of same radius and mass are R and M placed such that their centers are at common point an their planes are perpendicular to each other the moment of inertia of are axis passes about center perpendicular with one and same in plane with other 1 MR 2 2 2MR2 3 3 MR

3 0 315 x 10 5 4 0 035 x 10 5 22 A current of 5A flows downwards in a lon straight vertical conductor and the earth s horizonta flux density is 2x10 T then the neutral point occur 1 due north 10 cm from the wire 2 due east 10m from the wire 3 due east 5m from the wire 4 due west 5m from the wire

Two converging mirrors of same focal length fis placed at a distance d d 4f The number of image formed of an object placed midway between the mirrors 1 1 2 2 3 Multiple image will formed 4 No image will formed

to both of the Example 20 When ETTB and particle velocity is fields v uoi into a region of uniform electric and magnetic fields parallel to y axis i e E Solution Consider a particle of charge q and mass m released from the origin with ve B Boj The electric field accelerates the particle in y direction i e y component of velocity on increasing with acceleration Here and The magnetic field rotates the particle in a circle in xz plane perpendicular to magnetic field The resultant path of the particle is a helix with increasing pitch The axis of the plane parallel to y axis Velocity of the particle at time t would be and Here v t v i and U J U k Vy ayt constant v 0 wt Bq m 9E01 t m F v t vo cos y Ux Vo cos 0 V cos m t V Vo sin 0 vo sin a t 2 x rsin0 Similarly position vector of particle at time t can be given by r t xi yj zk qEo 2 m z r 1 cos 0 F mvo Bat i at j Bq m qEo m Bat m Bat 9 sin Jin Bat m vo sin Bqt m mvo TB 1 cos Bat Bq m k ZA 3 t 0 0 7 Vo

For a given surface the normal reaction and frictional force are inclined at NCERT I XI Pg 101 1 0 to each other 2 90 to each other 3 45 to each other 4 tan to each other A machine gun fires 10 bullets per second rith If the

Two small D q X Ao q 120 Bo q q C X E y identical electric dipoles AB and CD each of dipole moment p are kept at an angle of 1200 to each other in an external electric field E pointing along the x axis as shown in the figure Find the a dipole moment of the arrangement and b magnitude and direction of the net torque acting

The r m s value of alternating current is 10 A having frequency of 50 Hz The time taken by the current to increase from zero to maximum and the maximum value of current will be 1 2 x 10 2 sec and 14 14 A 2 1 x 10 2 sec and 7 07 A 3 5 x 10 sec and 7 07 A 4 5 x 10 ser and d 14 14 A

AT The angular momentum of a body having linear momentum P 21 3 4k at 1 0 2 about the point 2 3 4 is given by 21 6j 3k X61 3k L 61 3k 21 4j 6k Solution Answer 3 rxp 1 3 2

Q 10 An air bubble in glass slab u 1 5 when viewed from one side appears to be at 6 cm and from opposite side 4 cm The thickness of glass slab is 1 10 cm 3 15 cm 2 6 67 cm 4 None of these

par plate capacitor designed with a voltage rating of 1 kV using a material of dielectric constant 3 and dielectric strength about 107 V m For safety we would like the field never to exceed say 10 of dielectri strength What minimum area of the plates is required to have a capacitance of 50 pF

A particle is moving eastward with velocity of 5 m s In 10s the velocit changed by 5m s northwards The chang in velocity is 1 5 2 N W 3 2 3 N W 2 5 3 N W 4 3 2 x

Consider a uniformly charged wire that has the form of a circular loop with radius b Consider two points on the axis of the loop P is at a distance b from the loop s center and P2 is at a distance 2b from the loop s center The potential V is zero very far away from the loop At P and P the potentials are V and V respectively what is V in terms of V OP b b OP

7 In a Young s double slit experiment the fringe width is found to be 0 4 mm If the whole apparatus is immersed in water of 4 refractive index without disturbing 3 arrangement the new the geometrical fringe width will be i 1 0 30 mm 3 0 53 mm 2 0 40 mm 4 450 microns

A wire of mass m and length e bent in of an arc of a circle subtends an angle 0 at its centre Its moment of inertia 1 about an axis through centre of circle and normal to the plane of circle varies as 1 1 0 Xn 3 8 2 1 0 4 1 0

Given the interface between two materials Muscle and Bone see below and an initial KERMA of 100 J kg at the surface A of Muscle calculate KERMA at location B and C for 150 keV photons incident as shown below KA 100 J kg A Muscle 2 cm BC Bone 2 cm D

3 A straight conductor PQ is moving in a uniform and time independent magnetic field B as shown in figure The motional emf is equal to where v is velocity of rod 1 Bbv 3 Ba b X X X x X x 6x x X X X X X X X X X X x x x x X x X bx X X X X X x XX x X x X X a X X x X X x X X X X X x X X 2 4 Bav B ab X X X x X x X XQIX x X X x X x x X X X x

A soap bubble of radius R has uniformly distributed charge Q on it s surface It s energy is the self energy of charges surface energy due to surface tension In equilibrium this energy is minimum Surface tension is S Radius of bubble is R pressure inside is P pressure outside is Po 1 1 3 2 3 R R 0 128 0S 647 OS P Po 2S P P0 B 1 3

2 7 cm 3 10 3 cm 49 There is no flow of current between two charged bodies when connected because 2 They have the same potential 4 They have the same ratio of potential 1 3 cm 1 They have same quantity of charge 3 They have the same capacity 4 10 3 cm

3 Two long conductors are arranged as shown below 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 47 Assumes that the vacuum region in the center is small compared to the area of the conductors Conductor T

8 The speed time graph of a car is given here Using the data in the graph calculate the total distance covered by the car 30 a 1250 m b 875 m c 1500 m d 870 m 25 20 15 speed in m s 10 5 A B C 10 20 time in s D 30 E 40 H 50

Q 21 A capacitor of capacity 2 F is charged to a potential difference of 12 V It is then connected across an inductor of inductance 0 6 mH The current in the circuit at a time when the potential difference across the capacitor is 6 0 V is x 10 A to slo

Figure shows a potentiometer circuit for determining the mal resistance of a cell When switch S is open the balance point is found to be at 76 3 cm of the wire When switch S is closed and the value of R is 4 0 2 the balance point shifts to 60 0 cm Find the internal resistance of cell C C A C G J J B

a PRACTICE EXERCISE 1 6 Show that vectors a 4 0 1 b 1 3 4 and c 5 3 3 form the of a triangle Is this a right angle triangle Calculate the area of the triangle

The equation of a damped simple harmonic motion is kx 0 Then the angular frequency d x dt m b a 0 1 m of oscillation is k b c k dx m dt 2 4m 6 4m 1 2 1 2 d b 0 t h m d k m b 4m 1 2 b 4m n 2 1 2

a b c d the Column 1 and II Matrix Column I H Molecule H Ill Guill H CO CH CH OH CO H CO CH CH O C CO CH CH O C H OH H TEP X CO HH OH HO CO H H H CO H CO HH OH p q r s Column II Nature Chiral Achiral Meso Compound containing even number of chiral centers

10 In a YDSE setup screen is placed at a distance D of 1 44 meter from the slits Distance between the slits d is 0 144 mm and wavelength of light used is 288 nm L The approximate number of fringes between y 1 08 m and y 1 92 m is A 100 B 200 C 292 D 300

Light with an average flux of 20 W cm2 falls on a non reflecting surface at normal incidence having surface area 20 cm The energy received by the surface during time span of 1 minute is 10 10 J 12 10 J 24 10 J 48 10 J 1 2 3 4 e

Consider a small bar magnet undergoing simple harmonic motion SHM along the x axis A coil whose plane is perpendicular to the x axis is placed such that the magnet passes in and out of it during its motion Which one of the following statements is correct Neglect damping effects Induced e m f is minimum when the center of the bar magnet crosses the coil The frequency of the induced current in the coil is half of the frequency of the SHM Induced e m f in the coil will not change with the velocity of the magnet The sign of the e m f depends on the pole N or S face of the magnet which enters into the coil

5 Choose the correct options for the graph shown below E E Energy density Energy per unit volume of the medium r Distance of medium from a sound source A The power of the source will be decreasing with time if it is a plane source B The particles of the medium will have damped oscillations if the source is a plane so C The source must be a point isotropic source

30 An over head tank of capacity 10 k litre is kept at the top of building 15 m high Water falls in tank with speed 5 2 m s Water level is at a depth 5 m below ground The tank is 1 to be filled in hr If efficiency of pump is 2 67 5 electric power used is W

A conductor of mass m 5kg and length 4m is placed on horizontal surface and a uniform magnetic field B 2 Tesla exist parallel to horizontal surface but perpendicular to the conductor Suddenly a certain amount of charge is passes through it then it is found to jump to a height h 5m Then find the amount of charge that passes through the conductor in coulomb take g 10m s

A short electric dipole has dipole moment of 3 2x10 0C m The electric potential due to the dipole at a point which is at a distance 0 3 m from the centre of the dipole situated on a line making an angle of 45 with the dipole axis is 9x10 Nm C 1 4 o 1 300 V 3 200 V 2 30 V 4 20 V