Basic Physics Questions and Answers

3 71 A rod of length Im and mass 0 5 kg is fixed at one end is initially hanging vertical The other end is now raised until it makes an angle 60 with the vertical How much work is required Ans 1 225 1

Q 33 A radioactive isotope is being produced at constant rate X Half life of the radioactive substance is Y After sometime the numbers of radioactive nuclei become constant The value of this constant is Your Answer XY In 2 Option 1 XY In 2 Option 2 XY Option 3 XyIn 2 Option 4 Y Correct Answer XY In 2

ALLE CAREER INSTITUTE KOTA IMA JASTRE ALL INDIA OPEN TEST LEADER ENTHUSIAST COURSE JEE Advanced 03 02 2019 PAPER 2 In a series LR circuit connected to an alternating voltage source it is observed that at the instant voltage across the source is maximum voltage across the inductor is 3V and voltage across the resistance is 4V If resistance is 202 what is reactance in 2 of the inductor 000000 www

11 27 In a YDSE experiment two slits S and S2 have separation of d 2 mm The distance of the screen is D 8 5 m Source S starts moving from a very large distance towards S2 perpendicular to S S as shown in figure The wavelength of monochromatic light is 500 nm The number of maximas observed on the screen at point P as the source moves towards S is 3995 n The value of n is S14 m ioider Briw vg SIIS S2D P

A charged particle is kept at rest on a smooth horizontal surface in uniform mangetic field B which is directed vertically downwards as shown in the figure B X X X An observer is moving with constant velocity v towards right Then with respect to the observer which of the following statements is are correct A Path of the charged particle will be straight line B Path of charged particle will be circular C Magnetic force on the charged particle is zero D Magnitude of magnetic force on charged particle is qVB Pict out the WRONG statement 1 A and D 2 A and C

In a Wheatstone bridge shown in figure x y and A B The direction of the current between a and b will be A From a to b B From b to a a G c from a to b through c D from b to a through c B D C Your Answer Correct Answer

Solution Since the process is very fast and instantaneous or suddenly so there is no time to do evacuation is almost negligible SO there is no time to heat transfer so no heat transfer occurs So this process is Adiabatic process Q 24 Unpolarized light of intensity lo is incident on surface of a block of glass at Brewster s angle In that case which one of the following statements is true Your Answer transmitted light is partially polarized with intensity l0 2 Option 1 transmitted light is partially polarized with intensity l0 2 Option 2 transmitted light is completely polarized with intensity less than 10 2 Option 3 reflected light is completely polarized with intensity less than 1 2 Option 4 reflected light is partially polarized with intensity lo 2 Correct Answer reflected light is completely polarized with intensity less than 10 2

nderstanding what is the logic behind his marked part answer should be simply by the formula of electric field for infinit od but how they applied concept of yperbola lease help me hank you 1 03 pm 2 Which of the following graph shows curve between electric field E versus distance r from infinite line charge having constant positive charge density A B C D Solution D We know that due to infinite line charge of constant linear charge density A En 0 and E Enet So Enct E E Constant T 2kX Entr constant T since k and are constant zy constant 2kX T On taking Enet at y axis and r at z axis we get This is the equation of rectangular hyperbola Therefore the curve between E and r is a rectangular hyporhola 03m 31 S 88

A boat moves along the flow of river between two fixed points A and B It takes t time when going downstream and takes t time when going upstream between these two points What time it will take in still water to cover the distance equal to AB olution

13 In the figure there exists uniform magnetic field B directed into the plane of paper Wire CD is in the shape of an arc and is fixed OA and OB are the wires rotating with angular velocity to as shown in figure in same plane as that of arc point O If about at some instant OA OB 1 and each wire makes angle Y axis the current through 30 with 0 resistance R is wires OA and OB have no resistance B 1 A 0 C 1 Bo 2 2R 00 Y R wwww 30 30 O LOBS D Bol2 R Bol2 4R ant velocity A C

23 Light is incident at an angle o with the normal to a plane containing two slits of separation d Select the expression that correctly describe the positions of the interference maxima in terms of the incoming angle and outgoing angle 0 e a sino sine m 2 2 d b d sine m c sino sine m 1 2 d sino sine m d 0 AL

What does the orientation of axes exactly m ean Why does the value of scalar vector a nd its magnitude do not change when the or ientation of axes is changed but only the co mponent of vector changes please explain with images or any animation if possible

A coil of shape as shown in the figure is placed in a horizontal magnetic field of 1 956 Tesla perpendicular to field 0 01 amp Current in flowing in the coil It is free to rotate about axis AB Mass per unit length of straight wires is 2 and that of circular part is 2 2 where 2 805 gm cm What will be its magnitude of angular acceleration at t 0 5 cm 4 cm B R 4 cm

A tuning fork is used to produce resonance in a glass tube The length of the air column in this tube can be adjusted by a variable piston At room temperature of 27 C two successive resonances are produced at 20 cm and 73 cm column length If the frequency of the tuning fork is 320 Hz the velocity of sound in air at 27 C is 1 330 m s 2 339 m s 3 350 m s 4 300 m s

A horizontal wind is blowing with velocity v towards north east A man starts running towards north with acceleration a The time after which man will feel the wind blowing towareds east is hw hint wind ko rain maan A C V a V Ra B D 2v a 2v C

9 A monochromatic beam of electrons accelerated by a potential difference V falls normally on the plate containing two narrow slits separated by a distance d The interference pattern is observed on a screen parallel to the plane of the slits and at a distance of D from slits Fringe width is found to be When electron beam is accelerated by the potential difference of 4V the fringe width becomes 2 Find the ratio 1 Given d D 2

6 The average thermal energy for a mono atomic gas constant and T absolute is kg is Boltzmann temperature 3 kB T ms 3 4 kg T

Q 29 Potential difference between the points A and B in the circuit shown is 16 V then potential difference across 292 resistor is V volt VA VB 42 9V 12 3V A MW 20 12 32 wwwww B

8 The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is c speed of electromagnetic 1 1 c waves c 1 3 1 1 3 2 4 1 c

A shown in the figure a battery of emfe is connected to an inductor L and resistance R in series The switch is closed at t 0 The total charge that flows from the battery between t 0 and t t t is the time constant of the circuit is 1 1 1 EL R S a R el EL

A rectangular loop of wire ABCD is kept close to an infinitely long wire carrying a current I t 10 1 t T for 0 St ST and I 0 0 for t T Fig 4 EP 18 Find the total charge passing through a given point in the loop in time T The resistance of the loop is R In Fig 4 EP 18 XY is an infinitaly lana A FIGURE 4 EP 18 L L2

A spherical ball of mass M and radius R moving with a velocity V strikes elastically with a rigid horizontal surface at angle e to the normal Frictional coefficient assume that slipping occures while the sphere is in contact with the surface Change in angular speed during the collision 5 V sin 0 R 5 V cos 0 R a b c 4 V cose R d 4 V sine R

Light of wavelength is incident normally on a thin film The reflected light shows a minima for reflection The thickness of film is minimum possible Now the same film is placed in front of upper slit of the YDSE apparatus The fringe pattern shifts up by 7 5 mm the refractive index of material is Take D 5m d 0 1 mm 500nm A 1 25 B 2 5 C 1 5 D 1 75

1 The uniform additional pressure applied on a sphere is P How much its temperature should be raised to maintain its original volume The bulk modulus of elasticity of the sphere is and the coefficient of volume expansion is a

3 19 Assume that light of wavelength 600 nm is coming from a star The limit of resolution of telescope whose objective has a diameter of 2 m is 1 6 00 x 107 rad 2 3 66 x 107 rad 4 7 32 x 10 7 rad 3 1 83 x 10 7 rad 2

A straight wire of mass 100 g and length 50 cm carries a current of 1 A It is suspended in mid air by uniform horizontal magnetic field B The magnetic field B in tesla is 1 T 0 5 T 2T

5 A 900 pf capacitor is charged by a 100 V battery How much electrostatic energy is stored by the capacitor The capacitor is disconnected from the battery and connected to another 900 pf capacitor What is the electrostatic energy stored by the system How do you account for the difference in energy 7 A 80uf capacitor is charged by a 50V battery The capacitor is disconnected

A dip circle is used at magnetic equator and the plane of dip circle is perpendicular to magnetic meridian What will be reading of dip circle in this plane Options 0 0 O 90 o Its reading can be any angle 45

16 The energy levels of a certain atom for first second and third levels are E 4E 3 and 2E respectively A photon of wavelength is emitted for a transition 3 1 What will be the wavelength of emission for transition 2 1 1 3 02 32 1o easrobirli 2 42 3 4 32

19 Electric bulb 50 W 100 V glowing at full power are to be u in parallel with battery 120 V 102 Maximum number of bulbs that can be connected so that glow in full power is a 2 c 4 b 8 d 6

30 If the magnetic dipole moment of an atom of diamagnetic material paramagnetic material and ferromagnetic material are denoted by 1 respectively then 3 0 0 2 0 0 4 My 0 0

6 IESI PAPEO A ray is incident at an angle of incidence i on one surface of a small angle prism with angle of prism A and emerges normally from the opposite surface If the refractive index of the material of the prism is then the angle of incidence is nearly equal to 4 A 2 ANSWER A 2 3 2A P

The diagram below represents shallow water waves of wavelength 2 passing through two small opening A and B in a barrier How much longer is the length of path AP than the length of path BP E Wave motion B 0 32 Barrier d v Crest Trough D 42

U Potential energy of a particle of mass 1 kg free to move along x axis given as u x joule Total mechanical energy of particle is 4 joule Assuming only conservative forces are acting on particle maximum speed of the particle is 02ms 1 0 2 5ms 1 03ms 1 3 6 ms 1

6 Example 19 346 Chapter 9 Example 19 A large mass M and a small mass m hang at the two ends of string that passes through a smooth tube as shown The mass m moves around in a circular path which lies in the horizontal plane The length of the string from mass m to the top of the tube is L and 0 is the angle this length makes with the vertical What should be the frequency of rotation of mass m so that mass M remains stationary Solution O O L M Om K AT cos 8 0 T sin 04 O ma

2 26 A copper ball of density 8 6 g cm 1 cm in diameter is immersed in oil of density 0 8 g cm The charge in C on the ball if it remains just suspended in an electric field of intensity 3600 V m acting in upward direction is uc

Time period of a magnet is T If is divided in four equal parts such that each part has half of original length and half of cross sectional area then time period for each part will be Options 0 4T o T 4 OT 2

2x 14 The pair of physical quantities that have same units are 1 Average speed and instantaneous velocity 2 Average speed and average acceleration 3 Average acceleration and distance 4 Average acceleration and displacement

4 If both Assertion and Reason are false statements then mark 4 A Average speed for a motion is never less than the magnitude of average velocity R Distance travelled is never less than magnitude of displacement for a time duration

A satellite in an equatorial orbit not geostationary satellite of earth has time period of 6 hours At a certain instant it is directly overhead an observer on equator of earth It is directly overhead to the observer again observed after a time T The possible values of T are O 4 8 hour O 8 hour O Both 1 and 2 O Never

A train takes t sec to perform a journey It travels for sec with uniform acceleration then for n 3 sec with uniform speed v and finally it comes to rest with uniform retardation The n average speed of the train is V A 3 2 2n B 2n 3 2n C 3 2 3n D 2n 3 V 3n

in terms of number density of ree b A copper wire has a resistance of 10 ohm and an area of cross section 1mm A potential difference of 10V exists across the wire Calculate the drift speed of electrons if the number of electrons per cubic metre in copper is 8 x 1028 electrons

5 10 The length and breadth of a rectangular sheet are 16 3 cm and 10 1cm respectively The area of the sheet in appropriate significant figures and error is Final Results 2 SM 0 163 62 2 6 cm 3 27 163 62 3 cm 3 X 60 164 3 cm 3 13 163 6 2 6 cm 3

The velocity of a particle whose position time graph is as shown in the figure is 1 3 m s 1 3 m s X m 30 p 1 s 1 2 3 m s 4 2 m s

am confuse b w option 1 and 4 Pls explain In the circuit shown the switch is closed at time t 0 e 7 10 V 10 V S Which of the graphs shown below best represents the voltage across the inductor as seen on an oscilloscope 3 III 10 V Voltage 1 VI Voltage III R www Voltage 10 V Voltage 10 V 2 11 II IV KVPY SB SX 2011

5 Two dielectric slabs of dielectric constant are filled in between the two plates each of area A of the parallel plate capacitor as shown in the figure Find the net capacitance of the capacitor Area of each plate A 2 Area A

Ans 4 3 A cylinder contains hydrogen gas at pressure of 249 kPa and temperature 27 C Its density is R 8 3J mol K 1 0 02 kg m 3 0 2 kg m Ans 3 2 0 5 kg m 4 0 1 kg m

A particle is projected in such a way that it just passes over a wall and falls at other side as shown in figure The angle of projection o projectile is k 20 m Otan O tan tan 314 3IN WIN wall 60 m

40 27 For two mole of diatomic gas work done at constant pressure is W The heat supplied at constant volume for the same rise in temperature of the gas is 3 W 2 5 W 2 2 W W W P 4 points 28 Consider the process on an ideal gas as shown in figure The work done by the system B d 4 points

Assertion If power of an engine depends on mass angular speed torque and angular momentum then the formula of power is not derived with the help of dimensional method Reason In mechanics if a particular quantity depends on more than three quantities then we cannot derive the formula of the quantity by the dimensional method of If both Assertion and Reason are true and reason is the correct explanation of assertion If both assertion and reason are true and Reason is not correct explanation of assertion assertion is true but reason is false foloo