Basic Physics Questions and Answers

AHxn 23 9 kJ and a ASix 156 A nonspontaneous reaction has a J K Is 25 C a high temperature or a low temperature O 25 C is a low temperature O Whether this is a high or low temperature depends upon the number of moles of gases on the product side O 25 C is a high temperature Not enough information to determine

1 Two radioactive sample decay constant are 15x and 3x If they have same number of nuclei initially the ratio of number of nuclei after a time 3 N 4 ndations 1 2 i is

A variable capacitor and an inductive coil with negligible resistance are connected in series to an A C voltage of value 100 V The current in the circuit is 5 A When the capacitor decreases to half its value the current becomes 10 A The voltage across the capacitor in first case is A 40 V 50 V C 60 V 150 V B D

Three blocks of masses 2 kg 4 kg and 6 kg are connected by string and resting on a frictionless incline of 60 as shown A force of 120 N is applied upward along the incline to the 6 kg block If the strings are ideal the ratio T T2 will be g 10 m s 2 kg 4 kg Ti 60 6 kg T F

A man wishes to swim across a river 0 5 km wide If he can swim at the rate of 2 km h in still water and the river flows at the rate of 1 km h The angle made by the directon w r t the flow of the river along which he should swim so as to reach a point exactly opposite his starting point should be 1 60 2 120 3 145 4 90

In the circuit diagram given below five resistances of 10 22 40 22 30 22 20 22 and 60 2 are connected as shown to a 12 V battery Calculate a tatel 1002 www 4022 www HE 12V 3002 www 2002 ww 6002 wwwww

27 identical cells each of 10 V and 3 0 are used in a circuit 3 cells are joined in series to form a line and 9 such lines are connected to an external resistance R If the value of R is adjusted such that power P dissipated through it is maximum then P 900 W O P 150 W OP 225 W O P 750 W

The mass based ratio of U238 and Pb226 in a sample of rock is 4 3 If half life of U238 is 4 5 x 10 yr then age of the rock is 6 3 x 10 yr 4 5 x 10 yr 3 8 10 yr 6 2 x 10 yr Solution Answer 3 No N Number of atoms converted to lead No N 238N 226 No N 3 No N 1 79 No N Tin 4 5 109 In 1 79

4 In a series LCR sinusoidal AC circuit the source voltage is measured as V 200sin 100nt and current in the circuit is measured as 10 sin 100st The rms value of wattless component of current is DE IN 3 10 1 2 2 4 5 10 312 40 41

Choose the incorrect statement out of the following O The relation V IR applies to ohmic as well as non ohmic conductors O The relation E 7 applies to all conducting devices where E is electric field is current density and a is conductivit Resistance of an ohmic conductor is constant at a given temperature Resistance of a non ohmic conductor is a function of applied voltage 0

A 6 V battery of negligible internal resistance is connected across a uniform wire AB of length 100 cm The positive terminal of another battery of emf 4 V and internal resistance 1 Q is joined to the point A as shown in figure If galvanometer shows zero deflection then 6 V A 4V 12 O AC 50 cm O AC O AC O AC 50 3 cm 100 3 cm 200 cm 3 B

A current carrying loop of radius R is placed in transverse magnetic field B as shown Tension developed in loop is X O AY TURB 2 2 RB T IRB Questions Each question has 4 choices 1 2 3 and 4 out of which only one is correct xB

Classify the phase change scenarios according to the direction of the heat flow in each case Heat is transferred from the water to the surroundings A cloud of steam condenses into liquid water A puddle of water evaporates Heat is transferred to the water from the surroundings A block of ice melts Answer Bank No net transfer of heat occurs A puddle of water freezes into ice A block of ice sublimates into water vap

A moving coil galvanometer of resistance 20 Q gives a full scale deflection when a current of 1 mA is passed through it It is to be converted into an ammeter reading 20 A on full scale deflection If a shunt wire of 0 005 Q only is available then what resistance should be connected in series with the galvanometer coil O 99 955 0 O 79 995 Q 59 295 0

A person moves from A to B along the half circular path of radius 100 m in 3 minutes What is the ratio of his average path length to the magnitude of his displacement

28 There is a small air bubble inside a glass sphere u 1 5 of radius 10 cm The bubble is 4 0 cm below the surface and is viewed normally from outside Find the apparent depth of the bubble 1 3 1 cm from the surface 2 2 cm from the surface 3 4 cm from the surface

A condenser of 10 uF and an inductor of 1 2 H are connected in series with an A C source of frequency 50 Hz The impedance of the combination will be A zero C 5 83 Q B LO 0 583 58 3 Q

A rod OA of uniform mass density and length L is hinged at O in a vertical plane Another square plate of same mass is attached with a point A of the rod as shown in the figure In case i square plate is free to rotate about point A and in case ii square plate is fixed at point A Now system is allowed to oscillate in vertical plane such that axis of rotation is horizontal and passing through point O Let T and T2 6 are the time periods in case i and case ii respectively If T T2 is m Find the 11 value of m L 4 A L 2

A beam consisting of protons and electrons moving at the same speed goes through a thin region in which there is a magnetic field perpendicular to the beam The protons and the electron O Will go undeviated Will be deviated by the same angle and will not separate Will be deviated by different angles and separate O Will be deviated by the same angle but will separate O

Online Mock Test Series for NEET 2020 D Three rods of identical cross sectional area and made from same metal from the sides of an isosceles triangle ABC right angles at B The points A and B are maintained at temperatures T and 2T respectively in the steady state Assuming that only heat conduction takes place temperature at point C is 3T 1 2 1 T B T 2 2 1

1 Dams storing water are thicker at the bottom than at the top 2 Some people suffer from breathle ssness when they visit hill statio n 3 Some people suffer from nose ble oding when they visit hill station

Example 2 5 A triangle ABC has its side AB 40 mm along positive x axis and side BC 30 mm along positive y axis Three forces of 40 N 50 N and 30 N act along the sides AB BC and CA respectively Determine magnitude of the resultant of such a system of forces

6 In the diagram BAC is a rigid fixed rough wire and angle BAC is 60 P and Q are two identical rings of mass m connected by a light elastic string of natural length 2a and mg If P and Q are in a equilibrium when PA AQ 3a then the least coefficient of friction between the ring and the wire is u Then value of 3 is elastic constant B 3a PO 3a

A nucleus of mass M at rest is initially in an excited state whose energy is AE above the ground state of the nucleus The nucleus emits a gamma ray of energy hv and makes a transition to ground state Now choose CORRECT statement s A The nucleus will recoil when it emits ay ray because of the conservation of linear momentum B The nucleus will not recoil when it emits a y ray because of conservation of linear momentum is not obeyed in such type of processes C The value of hy is less than E D The value of hy is greater than AE

A long thin wooden cylindrical pipe of radius R carrying a uniform surface charge density is rotating about its axis with an angular velocity that increases slowly with time t as kt where k is a positive constant Which of the following statements is are correct for the region inside the pipe Jor The magnetic field is not constant with time B The magnetic field is constant but not uniform and the electric field is uniform but not constant T DI total energy density due to both the fields varies with time Both the magnetic and the electric fields are uniform and constant

29 A charge q and mass m moving with velocity v enters a region of magnetic field B at an angle 8 Which of the following represents the correct graph for pitch w r t angle 0 1 Pitch K 0 Pitch 2 0 3 2 Pitch 6 0 Pitch L 4 betic field B

22 A block of mass 2 0 kg is pulled up on a incline of angle 30 with the If the block moves with an smooth horizontal acceleration of 1 0 m s2 the power delivered by the pulling force at a time 4 0 s after the motion starts is J s

A point source S is at origin of coordinate system emits a spherical sinusoidal wave in which electric field E is given by E A A P cos ut 2 v wt where r is the distance from S In addition there is a plane wave propagating along x axis This 2 X Both waves are incident on a flat screen wave is given by E A cos wt perpendicular to x axis at a distance D from the origin as shown in the figure Consider a point at a distance y D from x axis on screen If intensity at y 0 is lo then choose CORRECCT statement s by wt D D y D A Electric field at a point at a distance r from origin on screen is given A cos ut 2T cos ut 2 X X B Electric field at a point at a distance r from origin on screen is given by E 2A E 2A cos wt 2 cos wt 2 Tr C Intensity as a function y is given by I I cos DX D Intensity as a function y is given by I I cos ny

3 17 5 8 5 cm The spectra of a black body at temperatures 327 C and 627 C are shown in the figure If A and A bem the areas under the two curves respectively the value of A is A 1 3 81 16 27 8 E 627 C 327 C 16 4 81 T

An electric dipole is placed at an angle of 30 to a uniform electric field The dipole will experience a a translational force only in the direction of the field b a translational force only in a direction normal to the direction of the field c a torque as well as a translational force d a torque only

103 Two spherical conductors A and B of radii 1 mm and 2 mm are separated by a distance of 5 cm and are uniformly charged If the spheres are connected by a conducting wire then in equilibrium condition the ratio of the magnitude of the electric fields at the surfaces of spheres A and B is 1 2 1 2 1 4 3 4 1

2 11 A cylinder of radius R made of material of thermal conductivity K is surrounded by a cylindrical shell of inner radius R and outer radius 3R made of a material of thermal conductivity K The two ends of the combined system are maintained at two different temperature What is the effective thermal conductivity of the system 1 K K K K 3 Y 2 4 K 8K 9 8K K

Two sources A and B are sounding notes of frequency 680 Hz A listener moves from A to B with a constant velocity u If the speed of sound is 340 m s what must be the value of u so that he per second hears 10 beats a 3 5 m s S c 2 ms b 3 m s S d 2 5 m s 1

A board of mass M is placed on a rough inclined plane and a man of mass m walks down the board If the coefficient of friction between the board and inclined plane is the acceleration of the man such that plank does not slip is given by space for rough work Page 3

S 7 5 A wedge of mass M 2 m rests on a smooth mo horizontal plane A small block of mass mo rests over it at left end A as shown in figure A sharp impulse is applied on the block due to which it starts moving to the right with velocity v0 6 m s At highest point of its trajectory the block collides with a particle of same mass mo moving vertically downwards with velocity v 2 m s and gets stuck with it If the combined mass lands at the end point A of the body of mass M the length is cm Neglect friction take 8 10 m s 191kW riv B K 20 cm

3 3CE 16 In the circuit shown the current The value of resistance Ris 12 V 1 192 3 49 2V 4 40 galvanometer shows zero www R 592 2 20 4 99 Med

A car leaves station X for station Y every 10 minute The distance between X and Y is 60 km The car travels at a speed 60 km hr A man drives a car from Y towards x at speed of 60 km hr if he starts at the moment when one of the car leaves station X how many car would he meets on route Type NCERT

What is the r m s value of an alternating current which when passed through a resistor produces heat which is thrice of that produced by a direct current of 2 ampere in the same resistor A 6 A 2 A 3 46 A 0 66 A B D

A charge q and mass m moving with velocity v enters a region of uniform magnetic field B at an angle 8 Which of the following represents correct graph for pitch w r t angle 0 0 0 90 0 D O 0 0

Two charged conducting spheres of radii a and b are connected to each other by a wire What is the ratio of electric fields at the surfaces of the two spheres b a 6 AD d

7 A monoatomic gas undergoes a change of state b the process shown in the V T graph Find the mol specific heat capacity of the gas for th process R molar gas constant V 1 1 5R 2 2 5R A B T

A listener moving with uniform velocity towards a stationary sound source hears beep of sound of frequency 165Hz over a distance of 100m The actual frequenc emitted by the source is 155 Hz and the speed of sound is 330 m s Duration of beep emitted by source is A 4s B 5s C 6s D 7s

3 Two vectors OA Find vector AB Hint Draw the vectors then OA AB OB 21 1 OB 1 3 4 In the above problem find the angle OAB using dot product Hint use the vectors AO not OA and OB

PQ 80 The C M of a uniform card board cut in T shape as shown in figure is 5cm A B 12cm 10cm 2cm a 4 cm from A towards B b 4 cm from B towards A c 3 cm from B towards A d 3 cm from A towards B

A particle is acted upon by a force of constant ma which is always perpendicular to the velocity of the particle The motion of the particle takes place in a plane It follows that a its velocity is constant b its acceleration is constant c its kinetic energy is constant d it moves in a circular path

A particle of mass m is attached to a light string length 1 the other end of which is fixed Initially the string is kept horizontal and the particle is given an upward velocity v The particle is just able to complete a circle a The string becomes slack when the particle reaches

by poten ray spectrum obtained is shown in adjoining graph If the potential difference is reduced to U 3 the correct spectrum is Ka TH qu A X ray intensity for C 2 52 X ray wavelength 2 IM

5 A uniform metal rod of 2 mm cross section is heated from 0 C to 20 C The coefficient of linear expansion of the rod is 12 x 10 C its Young s modulus is 10 1 N m The energy stored per unit volume of the rod is 2 1500 J m 4 1440 J m 1 2880 J m 3 5760 J m 3

Two identical sleeves A and B each of mass m can slide without friction on a fixed horizontal rod A load C of mass 2m is suspended from the mid point of a light inextensible cord of length 1 3 3m connecting the sleeves A and B initially the sleeves are at a separation and the load is held motionless What can you conclude for subsequent motion after the load is released Acceleration of free fall is 10 m s A LB C B A Maximum speed of the sleeves is 10 m s BY Maximum speed acquired by the load C is 2 5 m s The load descends a height 1 5 m to acquire maximum speed Before the sleeves collide the net force on the system consisting of the sleeves the cord and the load becomes zero once

In another world instead of the Coulomb s law electric force F on a point like charge q due to anoth Qq 1 ar 4 point like charge Q is found to obey the following law F Here is a positive constant and I is the position vector of charge q relative to the charge Q B Q 1 ar 4 1 Line integral of this electric field E di over a closed path is also zero as in other world D Electric field due to a point charge Q is E C Gauss law E ds enclosed also holds true for this electric field 0 All the above statements are true but this electric field is not conservative