Physics Questions

A coil having n turns and resistance R 2 is connected with a galvanometer of resistance 4 R 2 This combination is moved in time t seconds from a magnetic field W weber to W weber The induced current in 2 the circuit is W W 2 1 5 Rnt 3 W W 2 Rnt 2 4 n W W 5 Rt n W W Rt

A simple pendulum has length 2m and a bob of mass 100 gram It is whirled in a horizontal plane If the string breaks under a tension of 10 N the angle made by the string with vertical is g 10m s A B O C D cos 0 4 cos 0 1 cos 0 05 cos 0 2

Define gradient of scalar function and explain it s geometrical significance If 7x y y x find grad at the point 1 3 2 Define divergence of a vector function and explain its physical interpretation by 2 7 1 considering a fluid flow through a rectangular parallelopiped Show that V

A light ray is incident on a plane mirror at ar angle of incidence of 30 as shown in the figure The mirror is rotated by 45 in the clockwise direction Calculate the angle by which the reflected ray deviates from its original path Incident Ray 30 I 1 I

AB is a potentiometer wire of length 100 cm and its resistance is 10 ohm It is connected in series with a battery of emf 2V and resistance 40 ohm If a source of unknown emf E is balanced by 40 cm length of the potentiometer wire the value of E is R 400 2V H A ww 40 cm C 1 E Only one option is correct B 0 8 V

18 An electric refrigerator extracts 2000 calories from ice tray The coefficient of performance is 5 Then work done by the compressor in Joule will be 2 1680 joules 4 2000 joules 1 400 joules 3 800 joules

For a particle performing S H M when displacement is x the potential energy and restoring force acting on it is denoted by E and F respectively The relation between x E and Fis OF A B2E F C x x 0 D F 2E x 0 x 0 X 0

The network shown in figure is a part of a complete circle If at a certain instant the current 1 is 5 A and is ncreasing at a rate of 103 A s then value of VB VA and current in 2 2 resistance are respectively 15V A 10 43481 5 mH men B

In system of two particles it is possible Energy of system is conserved but momentum of system is not conserved O Energy of system is not conserved but momentum of system is conserved O Both energy momentum of the system are conserved Both energy momentum of the system are not conserved

4 A parallel beam of light is incident from air at an angle a on the side PQ of a right angled triangular prism of refractive index n 2 Light undergoes total internal reflection in the prism at the face PR when a has a minimum value of 45 The angle 9 of the prism is A 15 B 22 5 0 n 2 R C 30 45

15 A particle is executing a simple harmonic motion Its maximum acceleration is a and maximum velocity is Then its time period of vibration will be B 2 B a b O a B c a d 2015

Question 16 If a direct current of value a ampere is superimposed on an alternative current I b sin wt flowing through a wire what is the effective value of the resulting current in the circuit dc a A O Only one option is correct a pas ac 71 2

17 The oscillation of a body on a smooth horizontal surface is represented by the equation X A cos cot where X displacement at time t frequency of oscillation Which one of the following graphs shows correctly the variation of a with t Here a acceleration at time t T time period M a T H H T b o c o d o T 2014

85 The equivalent resistance of the circuit between points A and B is Ao Bo 1 2R 3 3R www 2r 2r www www 4r 4r www 8r www 2 1 2 R 4 1 3 R 00 89 85 The equivalent resistance of the circuit b

A train is moving towards east and a car is along north both with same speed The observed direction of car to the passenger in the train is A East north direction B West north direction C South east direction D None of the above

A mono chromatic source emits parallel beam of light of power 60 W emits 10 8 photons s All these photons falls normally on a black surface and get absorbed The momentum of each photon and the force exerted by these photons on the surface respectively in S I units are

Figure shows a circuit containing three resistors X X2 X3 an ideal inductor an ideal capacitor and an ideal emf source connected as shown The resistors have resistance Reach the inductor has inductance L the capacitor has capacitance C and the emf source has emf Given R The switch is first connected to position 1 When charge on capacitor becomes half of its maximum possible value then switch S is connected to position 2 Current in resistance X3 just after shifting the switch from position 1 to position 2 is given L 5mH C 2 F R 1002 E 5V 5 1 R Xa R R X X

PART B Answer all the questions Each question carries 5 marks 1 Find the velocity and the position as functions of the time for a particle of mass m which starts from rest subject to the following force function F x F sinct where F and c are positive constants 12 5 2 51

relative density mersed What e top of wood of metal 14 13 it consists rical plug of of length 10 ottom of the up and the ermine the The float ssless P and 2p 7 49 The interf respectively lies at the point A in a U tube at rest The height of liquid column above A is 8a 3 where AB a The cross sectional area of the tube is S With what angular velocity the tube must be whirled about a vertical axis at a distance a such that the interface of the liquids shifts towards B by 2a 3 A a Figure 7 114 8a 3 2p B

circuit is in unbalanced condition as potential difference is same across ends of wire Although mathematically i have found potential difference across ab in terms of i and that current will from b to a as Vb Va but sir as AB is a wire connected in between circuit so potential difference across its ends should be zero and no current should flow through it theoretically pls explain that A foor m Mu 52 502 Nor

Q No 28 View In English A long straight wire carrying a current of 1 0 A is placed horizontally in a uniform magnetic field B 10 x 10 5T pointing vertically upward figure The magnitude of the resultant magnetic fiel points P and Q both situated at a distance of 20 cm from the wire in the same horizontal plane are respectively P 1 3 Correct Answer 2 Your Answer 4 BO zero 20 T 20 T zero zero zero 20 T 20 T

In a double slit experiment green light 5303 falls on a double slit having a separation of 19 44 m and a width of 4 05 m The number of bright fringes between the first and the second diffraction minima JEE Main 2019 Online is 1 09 2 10 4 05 3 04

An object comprises of a uniform ring of radius R and its uniform chord AB not necessarily made of the same material as shown Which of the following can not be the centre of mass of the object B

A 0 034 kg mass ping pong ball is dropped from a height 1 76 m in a place where gravity is 9 8 m s Air friction is negligible but it loses an energy of 0 14 J when it bounces What height does it return to on its first bounce m

4 Linear and rotational 29 A horizontal disc is rotating about a vertical axis passing through its centre If an insect moves from centre to rim then the angular momentum of the system 1 Decreases 2 Increases 3 First decrease and then increase 4 Remains constant gh Work

26 A piston arrangement pushes a liquid with speed of 2 cm sec The radii of container and its nozzle are 10 cm and 2 mm respectively The velocity of liquid coming out of the nozzle is 1 500 cm s 3 50 m s com r 2 mm 2 500 m s 4 500 mm s 3

Two bodies A and B of equal mass are suspended from two separate massless springs of force constant ki and ka respectively The bodies oscillate vertically such that their maximum velocities are equal The ratio of the amplitudes of body A to that of body B is A B C D k K2 k k

Problem 2 A bag with a mass of 5 kg is being held 3 m above the table and a ball with a mass of 2 5 kg held with a height of 2 m Which has a greater gravitational potential energy the bag or the ball acceleration due to gravity 9 8 m s2

A body performing simple harmonic motion has potential energy Pi at displacement Its potential energy is P2 at displacement x The potential energy P at displacement x x is P P A P P P P DP P2 2 P P B C

A concave mirror of radius of curvature 40 cm is placed at the bottom of a tank of water with its optical axis vertical and the mirror facing upward Find the distance from surface of water of the final image in cm of a bird flying over the tank at a height of 60 cm above the surface of water Depth of water in tank is 20cm

A pendulum performs S H M with period 3 second in a stationery lift If lift move up with acceleration the period of pendulum is g acceleration due to gravity A B C D 2 00 second 1 5 second 2 5 second 1 75 second

Question 14 Two concentric coplanner coils of turns n and n2 have radii ratio 2 1 respectively Equal current in both the coils flows in opposite direction If net magnetic field is zero at their common centre then n n2 is Only one option is correct A 2 1

A coin is placed on the horizontal plate Plate performs S H M vertically with angular frequency o The amplitude A of oscillations is gradually increased The coin will lose contact with plate for the first time when amplitude is acceleration due to gravity A B C D g 2013 zero w 8 0 g A 2

PCM signal is called as O The signals which are obtained by encoding each quantized signal into a quantized word The signals which are obtained by encoding each quantized signal into a analog word The signals which are obtained by encoding each quantized signal into a sampled word O The signals which are obtained by encoding each quantized signal into a digital word

Let 0 be the angle between vectors A and B Which of the following figures correctly represents the angle 0 1 tot B 0 0 B 2 4 B B A

An iceberg is floating partially immersed in sea water The density of sea water is 1 03 gm cm and that of ice is 0 92 gm cm What is the fraction of the total volume of the iceberg above the level of sea water In cann

Two projectiles A and B are projected simultaneously from towers of same height as shown in figure in same vertical plane then 20 m s A 37 50 m 15 m s 53 B Path of A seen by Bis straight line Path of B seen by A is a parabolic A and B collide at t 2 s A and B collide at t 5 s

5 8 A particle of mass m is projected at t 0 from a point P on the ground with speed v at an angle of 45 to the horizontal Find the magnitude and direction of the angular momentum of the particle at time tr v g Ans 3 nvo 2 2g

An electric kettle takes 4A current at 220V How much time will it take to boil 1kg of water from temperature 20 C The temperature of boiling water is 100 C Question Type Single Correct Type 1 2 3 4 12 6 min 4 2 min 6 3 min 8 4 min

A projectile is fired at angle of 45 with the horizontal Elevation angle of the projectile at its heighest point as seen from the point of proejection is A B tan 45 C 60 1 3 2 Correct Answer

glish A parallel plate capacitor of capacitance C is connected to a battery and is charged to a potential difference V Another capacitor of capacitance 2C is connected to another battery and is charged to potential difference 2V The charging batteries are now disconnected and the capacitors are connected in parallel to each other in such a way that the positive terminal of one is connected to the negative terminal of the other The final energy of the configuration is Options 1 O zero 2 O 3 O 25CV 3CV 2 9CV

I CH 4 CH C CH and H I CH 40 The most stable carbocation is and H 1 CH3 CH CH3 2 CH3 CH CH CH3 3 CH3 CH CH CH CH3 4 CH3 CH CH CH CH3 3 CH 8 42 CH is an 41 The most stable carbanion is consgab b 1 CH3 CH 1 Electrophile no radical 2 CH CH 4 CH CH 2 Nucleophile 4 Ambiphiles

The work done by a variable force is measured by taking an infinitesimal length element di dxi dyj dzk such tha W fF di A particle of mass 2 kg is being acted upon by a variable force F K x2y i x y2j The particle is taken from 0 0 to a a along different paths Based upon the above facts answer the following questions E 3 c du a Zero c 3n6 111 The work done to take the particle from 0 0 to a 0 to a a is a kas ka6 b 2 ka6 d LA

Two blocks A and B of masses m and 3m are held against a compressed spring on a frictionless horizontal floor with the help of a light thread When the thread is cut the spring forces bo the blocks away and finally the spring drops on the floor and the blocks recede away from each other A MOMOCODE B Which block leaves the spring first O Block A Block B Both the blocks leave the spring

Two identical satellites are at the heights R and 7R from the Earth s surface Then which of the following statement is incorrect r radius of the Earth 1 Ratio of total energy of both is 5 2 Ratio of kinetic energy of both is 4 3 Ratio of potential energy of both 4 4 Ratio of total energy of both is 4 and ratio of magnitude of potential to kinetic energy is 2

63 A solid sphere of mass m and radius R is released the top of an inclined plane such that it rolls down without slipping If the coefficient of friction is u and the angle of inclination is with the horizontal then the force of friction acting on the body is 1 mgcos 2 mgsin mgsin 3 2mgsin 3

ball 4 58 A 10kg hammer strikes a nail at a velocity of 12 5 m s and comes to rest in a time interval of 0 004 sec Find the impulse imparted to the nail and the average force imparted to the nail Ans 125 N s 31300 N dio od to tro 10o edi le vitossib

An asteroid in space initially at rest explodes into two pieces A and B which then move in opposite directions Piece A has less mass than piece B Ignore external forces Identify correct statements Piece A Piece B

O Mohan wears a special kind of a spectacle that produces an upright image on the retina then he will a see everything upside down 14 75e everything upright c initially see everything upside down but regain normal upright vision after a month d initially see everything upright but after a few hours see everything upside down

Choose the CORRECT statement Work energy theorem can not be applied if non conservative forces are doing work O Centre of mass of an object may lie outside the object For all the cases centre of mass is the point where whole mass of the system is assumed to be concentrate Velocity of centre of mass can be changed by internal forces