Basic Physics Questions and Answers

o free point charges q and 4 q are placed a distance x apart A third charge is so placed that all the three charges are in equilibrium Then Unknown charge is 4 q 9 Unknown charge is 9 q 4 It should be between them at x 3 from smaller charge DIt should be placed between them at 2 x 3 from smaller charge

d A particle initially at rest on a frictionless horizontal surface is acted upon by a horizontal force which is constant in size and direction A graph is plotted between the work done W on the particle against the speed of the particle v If there are no other horizontal forces acting on the particle the graph would look like 1 t 1 2 3 W W W W wwwwww

For an a c circuit containin only as shown The graph of inductive reactance X vs frequency f of an a c source is NCERT Pg 238 1 0 L mm E E sin wt 2 4 n

The distance from the earth to the moon can be measured very accurately by timing how long it takes a special beam of light to reach the moon and reflect back Find out the name of the beam of light that is used for this purpose Why can t an ordinary beam of light be used

The acceleration a of a particle starting from rest varies with time according to relation a at The velocity of the particle after a time t will be at a a B b Bt 2 1 c at Bt 2 d at B 2

on a rough inclined with constant speed v The power required to move the same block up the inclined plane with same speed v is plane of inclination minimum instantaneous 1 mgvsine 22maycos A mavcost MY 2maysine 2gh

4 As per given figure to complete the circular loop what should be the radius if initial height is 5 m T h 5m 1 4 m 2 3 m 3 2 5 m

Q 15 The displacement of a particle undergoing rectilinear motion along the x axis is given by 2t 21t2 60t 6 The acceleration of the particle when its velocity is zero is a 36ms 2 b 9ms 2 d 18ms 2 X c 9ms 2

Square roots having negative radicands may be multiplied after each negative is removed as an i outside the radical producing positive numbers from each pair if they have the same radicand after they are rationalized

An inductive circuit contains a resistance of 10 ohms and an inductance of 2 henry If an alternating voltage of 120 V and frequency 60 Hz is applied to this circuit the current in the circuit would be nearly 1 0 32 A 2 0 80 A 3 0 48 A

Read the following statements and choose the correct answer A For a freely falling body the average velocity is proportional to square root of height of fall B For a freely falling body the displacement in successive equal time intervals are in the ratio 1 4 9 C For a vertical projected body the displacement during the last second of time of flight changes with velocity of projection D For a body projected from the top of the tower the displacement of the body is negative when the body crosses the point of projection

A horse is harnessed to a sled having a mass of 211 kg including supplies The horse must exert a force exceeding 1220 N at an angle of 30 3 above the horizontal in order to get the sled moving Treat the sled as a point particle HINT a Calculate the normal force in N on the sled when the magnitude of the applied force is 1220 N Enter the magnitude XN b Find the coefficient of static friction between the sled and the ground beneath it X c Find the static friction force in N when the horse is exerting a force of 6 10 x 102 N on the sled at the same angle Enter the magnitude 526 67 N

Two putty balls of equal mass moving with equal velocity in mutually perpendicular directions stick together after collision If the balls were initially moving with a velocity of 45 2 ms 1 each the velocity of their combined mass after collision is NCERT XI 1 129 1 45 2 ms 1 2 45 ms 1 3 90 ms 1 Sing

161 A straight conductor carrying current i splits into two parts as shown in the figure The radius of the circular loop is R The total magnetic field at the centre P of the loop is 1 Zero 3 31 32 R inword 90 R 2 31 32 R outword 4 inword

Two negatively charged particles of unit magnitude and charge Q are placed along a straight line At what position will the system be in Check and state whether the system is stable or unstable equilibrium equilibrium 1 Point

A block of mass m is connected to a spring of force constant K Initially the block is at rest and the spring is relaxed A constant force F is applied horizontally towards the right The maximum speed of the block will be 1 2 3 2mK VEF mk mk 2F 00000000 m Smooth

In the shown arrangement of the experiment of a meter bridge if AC corresponding to null deflection of galvanometer is x then what would be its value if the radius of the wire AB is doubled 1 x 3 4x AL 3 R www C X R www G B 2 4 2x

For a satellite moving in an orbit around the earth the ratio of kinetic energy to potential energy is 1 2 2 3 2 4

Light of wavelength strikes a photosensitive surface and electrons are ejected with kinetic energy E If the kinetic energy is increased to two times i e 2E the wavelength must be changed to X where 1 X X 2 2 3 X 4 4 X 4

EXAMPLE 6 Two equal conducting spheres of negligible size are charged with 16 0 x 10 14 C and 6 4 x 10 4 C respectively and are placed 0 20 m part They are then moved to a distance of 0 50 m apart a Compare the forces between them in two positions b The spheres are connected by a thin wire What force does each now exert on the other

25 Kirchoff s I law and II law are the consequences of 1 Conservation of charge and energy 2 Conservation of current and energy 3 Conservation of mass and charge 4 Conservation of current and mass

A body projected vertically with a velocity u from the ground Its velocity 3th 1 At half of maximum height is u 2 3 At 1 3rd of maximum height is u 3 A 1 2 are correct C 3 4 are correct 2 At 4 of maximum height is 21 FE 4 At th of maximum height is B 2 3 are correct D 1 3 are correct 3 2

19 The value of 30 Joules min in a new system which has 10g 100cm and 1min as fundamental units is 1 Point O2 16 x 10 new units O 1 08 x 107 new units 1 08 x 108 new units 2 16 x 107 new units

The maximum height reached by the projectile is metres and the horizontal range is 12 metres Th velocity of projection in ms g is the acceleration due gravity 4 1 5 2 3 2 3 4

If v and a are in opposite direction speed decrease J BU C aR acceleration tan0 I 0 2 c 0 Speed goes on decreasing Magnitude of tangential acceleration a dt Magnitude of resultant acceleration a a a Direction of resultant acceleration with centripetal ac a L Direction of resultant acceleration with velocity vector o zu C Co do win

On a semicircular ring of radius 4R charge 3q is distributed in such a way that on one quarter q is uniformly distributed and on another quarter 2q is uniformly distributed Along its axis a smooth nonconducting and uncharged pipe of length 6 R is fixed axially as shown A small ball of mass m and charge q is thrown from one end of pipe with speed u The speed u so that ball will come out from the other end of pipe is 3q A u 40 Rm B u 2q 7q 40 Rm 3q C u21401c Rm 9q D u 40 Rm

O tolerance nominal size basic dimension all of the above is a numerical value used to describe the theoretically exact size true profile orientation or true position of a feature

164 The reading of an ideal voltmeter in the circuit shown is 200 300 1 0 6 V 2 0 V 2002 2002 2V 3 0 5 V 4 0 4 V

A particle with restoring force proportional to the displacement and resisting force proportional to velocity is subjected to a force F Fo sin wt If the amplitude of the particle is maximum for w w and the energy of the particle is maximum for w w then 1 w wo and w2 wo 2 w wo and w wo w2 3 w1wo and W2 wo 4 w wo and we wo

Q 12 A wheel of radius 1 m rolls forward half a revolution on a horizontal ground The magnitude of the displacement of the point of wheel initially in contact with the ground is a 2 b 2 d 012 diola in c 4 2 V TI

velocity v upward acceleration a Another person 2 of the same mass m as person 1 is standing on the same elevator The net work done on the person 1 as observed by person 2 within time t is 1 m g a vt at 2 mg vt at 3 0 4 ma vt at

In the shown circuit r 10 R 20 E 4 Volt L 1 H Current I I and I are shown in figure If switch is closed at t 0 then just after closing the switch E 2r 2r I 0 8 A I 0 6 A 4 0 41 12 E R Switch mmmmmm elleelle 2L

The pitch of a screw gauge is 1 mm and there are 100 division on its circular scale When nothing is put in between its jaws the zero of the circular scale lies 4 divisions below the reference line When a steel wire is placed between the jaws two main scale divisions are clearly visible and 67 divisions on the circular scale are observed The diameter of the wire is Answer Rate this question

In which of the following states is the potential energy of an electric dipole maximum State whether the dipole is in equilibrium or not 1 Point a c q E q E q q b d q F E q q E T q

19 A block of mass m is projected with speed v along th rough surface of an inclined plane of height h If block comes to rest at the top of the surface then work done by friction force is 1 mv 2 m gh v 3 mgh 4 m gh y

Question If two balls of masses m and m m 2m are dropped from the same height then the ratio of the time taken by them to reach the ground will be O O O O None of these 1 2 m m 1 1

In the following circuit the resistance of the voltmeter is 10 000 2 and that of the ammeter is 20 2 If the reading of the ammeter is 0 1 A and that of the voltmeter is 12 V then the value of R is 1 122 2 100 3 118 Q A 116 R

olume A monatomic gas at a pressure P having a V expands isothermally to a volume 3V and ther compresses adiabatically to the volume V the fina pressure of the gas is NCERT Pg 312 5 1 33 P 2 P 10 2 2 33 P 4 3 P 100 19

The ends of a rod of length are maintained at temperature Q and Q Q The thermal conductivity of rod at a point is given as K when Q temperature at that point of the rod Q Q as a function of x is Q

c LCM of and 124 d d HCF of a 710 c 161 and d d d 82 In YDSE d 2 mm D 2 m and 2 500 nm If intensities of two slits are lo and 91 then find intensity at y 6 mm b 10 d 41 83 In YDSE let A and B be two slits Films of thicknesses and its are placed in front of

If a charged spherical conductor of radius 10 cm has potential V at a point distant 5 cm from its centre then the potential at a distance 15 cm from the centre will be 1 Point O 1 3 V O 2 3 V O 3 2 V

The IV characteristics of a p n junction diode is shown If R and R be the dynamic resistance of the pn junction when i a forward bias of 1 volt is applied and ii a forward bias of 2 volts is applied R respectively then R mA 800 400 15 10 1 160 2 16 3 1 6 4 0 16 11 2 22 1 V volt

A point object O is placed at distance 20 cm from a biconvex lens of the radius of curvature 20 cm and 1 5 The final image produced by lens and mirro combination will be at 10 cm 1 10 cm from the mirror 2 20 cm from the lens 3 20 cm from the lens 4 15 cm from the mirror

please explain the given solution why is there no flux in z direction Also how did they calculate flux through ABCD Consider a rectangular prism with cross section of a right angled triangle as shown Co ordinates of vertices are A B C D and E are 2 0 0 2 2 0 0 2 2 00 2 and 02 0 respectively There exists an electric field xi Zvi k N C everywhere If charge enclosed by the prism is N then find the value of N Solution Answer 02 E B ol There will be no flux due to electric field in z direction Due to electric field in x direction ODCE 0 ABCD 1 xx 2x dx 2 Due to electric field in y dir OAD 0 OBCE 2x 2x1 x 2x 2 2

Question A body is thrown upwards and reaches half of its maximumheight At that position O O O its acceleration is constant its velocity is zero its velocity is maximum its acceleration in min

In the adiabatic expansion of an ideal gas select the incorrect statement NCERT Pg 312 1 There is decrease in temperature of the gas 2 There is decrease in internal energy of the gas 3 The work done is positive 4 The work done by gas is equal to heat supplied

3 In YDSE let A and B be two slits Films of thicknesses and f and refractive indices and 8 are placed in front of A and B respectively If HATA HAB then the central maxima will a not shift b shift towards A c shift towards B and c if to sha

A train carriage moves along the x axis with a uniform acceleration a an observer A in the train set a ball in motion on a frictionless floor of the carriage with a velocity v relative to the carriage The direction of v makes an angle with x axis let B be an observer standing on the ground outside the train The subsequent path of the ball will be 3 i a straight line w r t observer A iii parabolic w r t observer A A i ii are correct C ii iii are correct ii a straight line w r t observer B iv parabolic w r t observer B B i iv are correct D none of these

5 A car is moving on a horizontal circular track of radius 0 2 km with a constant speed If coefficient of friction between tyres of car and road is 0 45 then maximum speed of car may be Take g 10 m s 1 15 m s 2 30 m s 3 20 m s 4 40 m s

A coil of self inductance L is connected in series with a bulb B and an AC source Brightness of the bulb decreases when a a capacitance of reactance Xc XL is included in the same circuit b an iron rod is inserted in the coil c frequency of the AC source decreased d number of turns in the coil is reduced is