Basic Physics Questions and Answers

d a to the Carnot cycle of an ideal gas shown in the figure Let Wab We Wed and Wa represent the work done by the system during the processes ab b c c d and d a respectively Consider the following relations iii W a b p i W ii W Wb c Wc d Wa a b a a b Wc d cd 0 d a i and iii e i iii and iv V Wbc Wc d Wd a 0 Wd a 0 d a b C iv Wbc Wdra 0 b c Which of the above relation s is are true AMU 2012 b iii and iv d i i and

The temperature of the gas is increased from 120 K to 480 K If at 120 K the rms speed of gas molecules is VRMs then at 480 K it becomes NCERT Pg 325 1 4 VRMS 3 VRMS 2 2 VRMS 4 VRMS 2

4 6 beats per second with intensity relation between maxima and minima equal to 9 A tuning fork vibrating with a sonometer having a wire of length 20 cm produces 5 beats per second The beats frequency does not change if the length of the wire is changed to 21 cm The frequency of the tuning fork must be 1 200 Hz 3 205 Hz 2 210 Hz 4 215 Hz 50

7 A man standing on a platform observes that the frequency of the sound of a whistle emitted by a train drops by 140 Hz If the velocity of sound in air is 330 m s and the speed of the train is 70 m s the frequency of the whistle is 1 571 Hz 2 800 Hz 3 400 Hz 4 260 Hz

An observer is approaching with a speed v towards a stationary source emitting sound waves of wavelength A The wavelength shift detected by the observer is Take c speed of sound A C 1 3 dov C Ak 2 4 Zero

A convex lens of focal length 10 cm form real image of an object The distance between the object and the image may be 1 25 cm 2 30 cm 3 38 cm 4 50 cm 1 2 inn reacon from below 3 4

92 Waves 43 A train blowing its whistle moves with const speed on a straight track towards observer a then crosses him If the ratio of difference betwe the actual and apparent frequencies be 3 2 in two cases then the speed of train is v is spe of sound 1 3 2v 3 1 3 N 4 3v 2 44 A man is standing on a railway platform listen

of two ideal gases under ideal conditions of same temperature pressure and volume the ratio of mean free paths of molecules having molecular diameter 1A and 2 is NCERT Pg 337 1 2 1 2 4 1 3 1 4

5 A block of mass 2kg is kept inside a cube as shown The cube is moving in vertical plane with velocity Sr 21 m vertical plane with velocity V 5t i 2t j m s Block remains at rest inside the cube with respect to the cube Force exerted by cube on the block is 13n Newtor y Find n m 2kg X 9 8 10m s

When a capillary tube is dipped in a liquid the liquid rises to a height h in the tube The free liquid surface in the tube is hemispherical in shape The tube is now pushed down so the height of the tube outside the liquid is less than h Then the NCERT Pg 265 1 Liquid will come out of the tube in the form of small fountain 2 Liquid will ooze out of the tube slowly 3 Free liquid surface inside the tube remain hemispherical 4 Liquid will rise to the top of capillary tub increase the radius of curved surfac and stay there

48 During an adiabatic process the cube of the pressure is found to be inversely proportional to the fourth power of the volume Then the ratio of specific heats is Manipal 2012 a 1 c 1 67 P 32 b 1 33 d 1 4

14 If a gas expands with temperature according to the relation V KT2 3 then what will be work done when the temperature changes by 30 C BCECE Mains 2012 d 10 R a 40 R b 30 R c 20 R

4 Sphere will never attain terminal velocity m 20 The sap in tree rises in a system of capillaries of radius 2 5 x 10 5 The surface tension of sap is 7 28 x 10 2 N m and the angle of contact is 0 The maximum height to which sap can rise in a tree through capillary action is density of sap is 1 x 10 kg m NCERT Pg 265 1 0 21 m 2 0 59 m 3 0 87 m 4 0 91 m

Two plane mirrors a source S of light emitting monochromatic rays of wavelength and a screen are arranged as shown in figure If angle is very small the fringe width of interference pattern formed on screen by reflected ray is a b x A B a 2a b 2 S C screen b 2a b 2 D a b 2

A body is projected from a tower with speed lesser than escape speed 0 v v Then A The body will reach a certain height and then will fall down following a straigh line path B The body will reach a certain height and then will fall down following a parabolic path C The body may have positive total energy D The body may orbit the earth in a circular orbit

Waves 191 The string of a violin emits a note of 205 Hz at its correct tension The string is tightened slightly and then it produces six beats in two seconds with a tuning fork of frequency 205 Hz The frequency of the note emitted by the taut string is

As 200N force acting on A only For body B we will not consider force 200 N as it is not act ing on B directly Pls explain these 2 doubts Two bodies A and B of mass 5 kg and 10 kg in contact with each other rest on a table against a rigid wall The coefficient of friction between the bodies and the table is 0 2 when the force of 200 N is applied horizontally on A Which of the following is correct 200 N A B

35 Two sound waves of intensity 2 W m and 3 W m meet at a point to produce a resultant intensity 5 W m The phase difference between two waves is 1 KIN 2 2 4 Zero 41

3 1 B 2 B 4 2 B 1 B In a double slit experiment to find the separation between slits by displacement method the separations of images of slits were found to be 16 mm and 9 mm respectively The actual separation between slits will be 3 0 37 In Fr first radi the 1 12 5 mm 2 12 mm 3 3 5 mm 4 144 mm 32 A double slit experiment is performed with light of velength 500 nm A thin film of thickness 2 um troduced in the path of SI JO 38

Marks 4 A man can swim at 2 m s in a swimming pool He enters a 100 m wide river at or bank and swims at right angles to the riv flow velocity w r t water If his drift a reaching the other bank is 40 m calcula

8 A flask contains argon and chlorine in the ratio of 2 1 by mass The mixture temperature is 300 K What is ratio of root mean square speed of molecules of two gases NCERT Pg 330 Atomic mass of argon 39 9 u and molecular mass of chlorine 70 9 u 1 1 33 2 1 55 3 1 77 4 1 66

a Show with Dirac notation that the eigenvalues of a hermitian operator are real and the eigenvalues are orthogonal b Show with Dirac notation that the eigenvalues of a unitary matrix are unimodular and its eigenvectors are orthogonal

may this effect may be ob 1 10 6 m 2 10 m 4 10 8 m 3 10 10 m When white light is incident normally on an oil film of thickness 104 cm and refractive index 1 4 then the wavelength which will not be seen in the reflected system of light is 1 7000 A 3 4000 A 2 5600 4 All of these Imperfections in optical lenses can be observed with the help of wa and the m 15 0 Dif 33

3 expansion of copper with temperature 1 4 6 10 K 2 tions 10 3x10 Kaf 3x10 K 6 10 K 3 10 Ka 6 10 K ndency of coefficient of volume gives the 3 10 K 250 250 250 NCERT Pg 281 500 T K 500 T K 500 T K

1 The volume contraction of a solid copper cube 10 cm on an edge when subjected to a hydraulic pressure of 107 Pa is B 140 10 N m 2 NCERT XI Pg 248 X 1 0 07 cm 2 0 03 cm 3 0 02 cm 4 0 01 cm

Three straight parallel current carrying conductors are shown 1 30A in the figure The force experienced by the middle conductor of length 25 cm is A 9 x 104 N toward left B 6 x 104 N toward left C zero D 3 x 104 N toward right 3cm 12 20A 5cm I 10A 201

A 0 5 Kg mass is attached to the end of a spring with stiffness 25N m The damp ing constant for the system is 1 N sec m If the mass is pushed 0 5 m above the equilibrium position and given an upward initial velocity of 3 m sec when will the mass first return to the equilibrium position

4 2 0 5 The density of water at a depth where pressure is 80 0 atm Given density at the surface is 1 03 x 103 kg m B 2 2 x 109 N m NCERT XI Pg 248 1 1 034 10 kg m 2 1 34 x 10 kg m 3 3 1 64 x 10 kg m 3 4 2 084 x 10 kg m

The displacement of a particle in S H M is x asinet Which of the following graph between displacement and time is correct A E A M M F 1 A 2 B 3 C 48 In Question 47 which of the graph between velocity and time is correct 1 A 2 B 4 D 3 C 4 D 49 In Question 47 which of the graph between kinetic energy and time is correct 1 A 2 B 3 E 4 F 50 In Question 47 which of the graph between potential energy and time is correct 1 A 2 B 3 E 4 F 51 In Question 47 which of the graph between acceleration and time is correct 1 A 2 B 3 C 4 D 52 In Question 47 if the displacement of a particle executing SHM is x a cosest which of the graph between displacement and time is correct 1 A 3 C 2 B 4 D 53 In question 52 which of the graph between velocity and time is correct 1 A 2 B 54 3 C 4 D In question 52 which of the graph between acceleration and time is correct 1 A 2 B 3 C 4 D 55 In question 52 which of the graph between K E and time is correct 1 A 2 B 3 E 4 F 56 In question 52 which of the graph between P E and time is correct 1 A 2 B 4 F 3 E

20 Two wires of diameter 0 25 cm one made of steel and the other made of brass are loaded as shown in the figure The unloaded length of steel wire is 1 5 m and that of brass is 1 0 m The ratio of tensile stress in steel to brass wire is g 10 m s 111 ti 1 2 3 N W NG 69 4 Steel 1 5 m 6 0 kg Brass 1 0 m 4 0 kg INCERT XI Pg 248

4 Square of tem A box filled with hot tea cools from 94 C to 86 C in 4 minute when room temperature is 40 C How long will it take to cool from 71 C INCERT Pg 297 to 69 C 1 10 minute 2 3 minute 3 100 second

4 56 An electron is accelerated through a potential difference V enters into a uniform transverse magnetic field and experiences a force F if the accelerating potential increased to 2V the electron in the same magnetic field will experience a force A F C 2F B F 2 D 2F

18 A 15 kg mass fastened to the end of a steel wire of unstretched length 1 0 m is whirled in a vertical circle with an angular velocity of 4 radian s at the bottom of the circle The cross sectional area of the wire is 0 065 cm The elongation of the wire when the mass is at the lowest point is g 10 m s NCERT XI Pg 248 2 2 05 mm 4 3 05 mm cal 1 1 93 mm 3 1 65 mm

4 3 78 um In Young s double slit experiment shown in figure and S are coherent sources and is the scree having a hole at a point 1 0 mm away from the centre line White light 400 to 700 nm is sent through the slits Which wavelength passing through the hole has strong intensity 1 0 5 mm S S 1 400 nm 2 700 nm 3 500 nm 50 cm hole centre of screen T 1 0 mm screen S

1 12 3 24 2 18 4 30 A thin film of water u 4 3 is 3100 thick If it is illuminated by white light at normal incidence The colour of film in the reflected light will be 1 Blue 2 Black 3 Yellow 4 Red The central fringe of the interference pattern produced by light of wavelength 6000 A is found to shift to the ht fringe after a glass plate of refractive in Young s

A vertical U tube of uniform inner cross section contains mercury in both sides of its arms A glycerin density 1 3 g cm column of length 10 cm is introduced into one of its arms Oil of density 0 8 gmcm is poured into the other arm until the upper surfaces of the oil and glycerin are in the same horizontal level Find the length of the oil column Density of mercury 13 6 g cm a 10 4 cm b 8 2 cm c 7 2 cm d 96 cm Glycerine 8 04 10 cm Oil h

T length then the ratio of tension in string 1 Two particles each of mass mare moving in horizontal circle with same angular speed If both strings are of same 1 3 3 2 2 4 Infinite is 2 3 4 3 breje T my 5 Dond Office Aakash Tower 8 Pusa Road New Delhi 110005 Ph 011 4

4 450 Hz 31 An aluminium rod having a length 100 cm is clamped at its middle point and set into longitudinal vibrations Let the rod vibrate in its fundamental mode The density of aluminium is 2600 kg m and its Young s modulus is 7 8 x 10 0 N m The frequency of the sound produced is 2 2740 Hz 4 1685 Hz 1 1250 Hz 3 2350 Hz

25 The equation of a standing wave in a string fixed at both ends is given as y 2 A sin kx cos cof The amplitude and frequency of a particle vibrating at the mid of an antinode and a node are respectively 1 A 3 A 00 2 0 K A 00 2 2 2 4 2 A 2x 26 Two sinusoidal waves given below are supermosed 29 In cre 1 2 3 4 30 Tw y Y TH

2 If 1 x x a a x a x Column I Te A a a a 2n B a a a a3 a2n P C ao 2a 3a 2n 1 a n D a 2a 4a2 8a3 2 a n 2n 2n a x then 2n Column II P n 1 Q 1 R 3n S 3

12 A travelling wave pulse is given by 3x2 4812 24xt 2 where x and y are in metre and it is in second velocity of wave is 1 4 m s 3 2 2 m s 4 12 m s

15 Molar specific heat of an ideal gas at constant volume is 21 joule mol K and molar specific heat at constant pressure is about 35 joule mol K The ideal gas is NCERT Pg 314 1 Monoatomic 2 Diatomic 3 Triatomic 4 Polvatomic

A satellite of mass m is in a circular orbit of radius 2RE around the earth The energy required to transfer it to a circular orbit of radius 4RE IS NCERT Pg 196 1 121 mgRE 2 mgRE 2 mgR 8 mgRE A

An object with a mass of 10kg moves at a constant velocity of 10m s A constant force then acts for 4sec on the object and gives it a speed of 2m sec in opposite direction The acceleration produced in it is

Q12 Physics Section B Centripetal acceleration in uniform circular motion is A B C A constant vector Not a constant vector A constant scalar D A magnitude changing vector

vclist traversed half the distance of a linear track with a velocity 10 m s The remaining part of the track was covered with a velocity v for half the time and a velocity v for the other half of the time If v v 20 m s then the average velocity of the cyclist during the completion of the journey through the track is

2 What is the minimum energy required to launch a satellite of mass m from the surface of a play 201 of mass M and radius R in a circular orbit at an altitude of 2R GmM 2GmM 2 1 2R 5GmM 3 6R 3R GmM 3R 4 th towards sun when the moon comes from the of the

Which of the following statement s is are not correct i Coloured components of mixture are separated by chromatography ii Separating funnel works on the basis of difference in boiling point iii Components of colloidal solution are separated by crystallisation iv Carbon dioxide is impure substances Options i iii and iv ii iii and iv i ii and iii i ii and iv

4 A particle of mass m and charge q moves with a constant velocity v along the positive x direction It enters a region containing a uniform magnetic field B directed along the negative z direction extending from x a to x b The minimum value of v required so that the particle can just enter the region x b is 2002 2M qbB no DA 21 a m c gaB m b 9 b a B m d 9 b a B 2m

Ignition temperature is the lowest temperature at which a substance catches fir Identify the correct option regarding the ignition temperature of a good fuel Ide fuel Options Ignition temperature should be below room temperature Ignition temperature should be above room temperature Ignition temperature should be equal to 100 C Ignition temperature should be equal to room temperature