Physics Questions

kinetic energy 4 mu of the molecules p is not always equal to p The average of a squared quantity is not necessar the square of the average Can you find examples for this statement

The electric field in an electromagnetic wave is given by E 50 N C sino t x c Find the intensity of the wave 1 3 3 W m 3 2 4 W m 2 4 8 W m 4 3 9 W m Telegran

A potential difference of 600 V is applied across the plates of capacitor the separation between the plates is 3 cm An electron is projected parallel to plates with velocity 2 x 105 m s moves undeflected The magnitude of magnetic field between capacitor plates is 0 4 T 0 3 T 0 2 T 0 1 T

20 A circuit containing resistors and an inductor Find the values of i soon after the switch S is closed and long after the switch S is closed 150 V 20 22 60 22 1 1 7 A 2 8 A 40 22 wwwww 3 H 00000000 S 2 1 2 A 24 A

Two spheres A and B of exactly same initial mass are given equal positive and negative charges respectively Their masses after charging Remains unaffected Mass of A mass of B Mass of A mass of B Nothing can be said

A wheel having moment of inertia 12 kg m about an axis is rotating at 180 rpm If the wheel is stopped in a time of 10 second how much average retarding torque is applied 14 5 Nm 22 6 N m 36 5 Nm

Two beams of light having intensities 41 and 9 interfere to produce an interference pattern on a screen The phase difference between the beams is 2 at point A and at point B Then the difference between the resultant intensities at points A and B on the screen is NI find N 12

Photoemission by Black Body Radiation A black body emits peak spectral intensity at 9000 On increasing its temperature total radiation power increases by 81 times At the initial temperature when peak radiation of black body is allowed to fall on a metal surface assume other radiation are blocked by a filter it does not cause any photoemission but after increasing temperature the peak radiation of black body causes electrons come out which are stopped by a potential equal to the excitation energy of H atoms for n 2 to n 3 Bohr level Find work function of metal

De excitation of a moving hydrogen atom Consider a hydrogen atom with its electron excited to nth state moving at speed v c It emits a photon in the direction of its motion and changes its state to a lower state m If atom is kept at rest then for the transition from n to m state a frequency vo is emitted find the frequency of emitted photon in case when atom is moving

There may or may not be mass at the centre of mass of an object The linear velocity of each point of rigid body rotating about a given axis is same The angular velocity of each point of rigid body rotating about a given axis is different I 0

Same mass of copper is drawn into two wires of radius 1 mm and 3 mm Two wires are then connected in series and current is passed through them Heat produced in the wires is in ratio of 3 1 9 1 81 1

4 5 A moderator C control rods One thousand nuclei of U 235 fission in given time The total number of neutrons emitted in these fission reactions is close to A 1000 C 2000 B coolant D reactor core The atom bomb is based on A chemical reaction C nuclear fusion B 1500 D 2500 B nuclear fission D atomic collision The temperature of the material undergoing nuclear fusion sho 100 K

25 Eight equal point charges are placed at corners of cube of side length a The potential and electric fie magnitude at the centre of cube will be 4q 1 3 RE 3 0 0 0 4q 4q 2 3 x 3m a 4 0 4q 3 m

From a uniform circular disc of radius R and mass 9M a small R disc of radius is removed as shown in the figure The 3 moment of inertia of the remaining disc about an axis perpendicular to the plane of the disc and passing through centre of disc is 37 M 1 9 40 MR2 2 4 MR 4 10 MR R

A rod of mass 3 kg with length of 2 m is rotating about an axis perpendicular to its length and passing through its centre of mass If the angular speed of the rod is 10 rad s then what is its rotational kinetic energy O 50 J O 100 J 150 J 200 J

Two identical sources P and Q emit light waves in same phase and of same wavelength Distance between P and Q is 32 The maximum distance from P along the x axis at which a minimum intensity occurs is given by k times find k PL X 8 75

5 n identical cells are joined correctly in series with another two cells A and B with reverse polarities Emf of each cell is E and internal resistance is r Potential difference across cell A is n 4 2E 1 25 n 1 1 1 2 2E 1

Multiple Isotopes in a Radioactive Sample A sample of uranium is a mixture of three isotopes U234 U235 and U238 present in ratio of 0 006 0 71 and 99 284 respectively These have half lives 2 5 x 105 years 7 1 x 108 years and 4 5 x 10 years respectively Calculate the contribution to activity in of each isotope in sample

spring as shown in figure The magnitudes of acceleration of A and B immediately after the spring is cut are respectively Junge 3m m LE 3m g g g g 3 3 8 0 0 m g pol m g Two blocks of masses 3m and m respectively are connected by a massless and inextensible string The whole system is suspended by a massless spring as shown in figure The magnitudes of acceleration of A and B immediately after the spring is cut are respectively 3 g 6 0 g g g g g 3 3 pol m g 3

15 The volume V of a monatomic gas varies with its temperature T as shown in the graph The ratio of work done by the gas to the heat absorbed by it when it undergoes a change from state A to state B is 3 8 1 A 2 B T alm

SI unit of electric current ampere is the current which when flows through each of two parallel wires spaced 1 m apart in vacuum and of infinite length will give rise to a force between them equal to O 1 N m O 4 x10 7 N m O 2x10 7 N m 110 7 Nim

A ball is fired perpendicularly from an inclined plane towards another plane as shown If it also strikes the second plane perpendicularly Find i Time of flight ii Velocity iii Displacement AB Pe 253 sec 10 3 m sec A 90 60 10 3 m sec A 90 60 Glamone 30 B 30 B Ved JE D Vede JE

43 A 10 eV electron is circulating in a plane at right angles to a uniform field of magnetic induction 10 Wb m 1 0 gauss the orbital radius c electron is 1 11 cm 2 12 cm 2 18 cm 4 16 cm

42 Pendulum A is x cm shorter than a seconds pen dulum and pendulum B is x cm longer than the seconds pendulum The ratio of their time periods is 3 4 The length of the pendulum with higher frequency is

An external resistance R is connected across a battery of e m f E and internal resistance r Determine the condition for which the production of heat in R will be maximum A galvanometer of resistance 45 ohm shunted with a resistance of 5 ohm is joined in series with a resistance of 84 ohm and a battery of e m f 4 5 volt having internal resistance 1 5 ohm Find the current passing through a the battery b the galvanometer and c the shunt 2 3

Which of the following graph best represents the variation of impedance IZ of parallel LC circuit with co 1Z1 IZI 1 3 121 LC LC 00 4 N 0 121 LC IC 0 8

Electrical Energy Power Potential Difference 10 In the circuit shown the thermal power dissipated in R is P The thermal power dissipated in R is R R 1 P 3 2 P 3 L www R R R 2R 2 4P 9 10

23 If the electric potential in a region is represented as V 2x 3y 4z Then electric field vector will written as 1 2 3 4k 3 2 3 4k 2 21 3 4K 4 2 3 4k

An air cored solenoid having a length of 30 cm whose area is 25 cm and the number of turns is 500 And the solenoid has carried a current of 2 5 A Suddenly the current is turned off and the time is taken for it is 10 3 8 What would be the average value of the induced back emf by the ends of the open switch in the circuit Neglect the variation in the magnetic fields near the ends of the solenoid 1 5 5 V 2 4 5 V 3 6 5 V

A beam of unpolarised light of intensity is passed through a polaroid A and then through another polaroid B which is oriented so that its principal plane makes an angle of 45 relative to that of A If intensity of the emergent light is then value of Nis 4 10 N y

A body cools from a temperature 3T to 2T in 10 minutes The room temperature is T Assume that Newton s law of cooling is applicable The temperature of the body at the end of next 10 minutes will be NEET II 2016 4 T 3 T Correct

10 In an am 0 2 of main current pass through the galvanometer If resistance galvanometer is G the resistance of ammet will be a c 1 499 G 1 G 500 b d 499 G 500 500 499 G

Two infinite long parallel wires A and B carrying currer 10 A and 20 A respectively in opposite direction are placed at a separation of 30 cm The magnetic field will be zero at 10 cm from A between the wires 10 cm from B between the wires 30 cm from A outside the wires 30 cm from B outside the wires

De Exitation by Emitting Two Photons A hydrogen like atom of atomic number Z is in a higher excited state of quantum number n The excited atom can make a transition by emitting two photons of energies 10 2 eV and 17 eV respectively An atom in same excited state can make a transition to n 3 by successively emitting two photons of energies 4 25 eV and 5 95 eV respectively Calculate the values of n and z

A 4 pole d c generator has a wave wound armature with 792 conductors The flux per pole is0 0121 Wb Determine the speed at which it should be run to generate 240 V on no load

An ocean going vessel uses sonar to measure the depth of the ocean If a sound wave sent from the ship bounces off the ocean floor 525 0 m below and returns to the ship after 0 875 seconds then what is the speed in m s of the sound waves in water Enter a numerical answer with three significant figures

A proton moving with a constant velocity passes through a region without change in its velocity If E and B represent electric and magnetic field respectively Then this region of space may not have O E 0 B 0 O E 0 B 0 O E 0 B 0 E 0 B 0

A mass m moves with a velocity v and collides inelastically with another identical mass After collision the 1st mass moves with velocity v 3 in a direction perpendicular to the initial direction of motion Find the speed of the 2nd mass after collision 1 V 3 2v 3 2 3 v 4 v 3 Before collision v v3 After collision 1000

A particle moves along a straight line x At time t 0 its position is at x 0 The velocity V of the object changes as a function of time t as indicated in the figure t is in seconds V in m sec and x in meters a What is x at t 3 sec b What is the instantaneous acceleration in m sec at t 2 sec c What is the average velocity in m sec between t 0 and t 3 sec d What is the average speed in m sec between t 1 and t 3 sec V m sec 3 2 1 0 1 2 3 t sec 2

A train is moving at a constant speed along a straight level track Then a the frictional force is zero b the resultant of all the forces acting on the train is zero c the pushing force is greater than the frictional force d the frictional force on the engine and the coach acts in the same direction

U A long solenoid carrying a current I is placed with its axis vertical as shown in the figure A particle of mass m and charge q is released from the top of the solenoid Its acceleration is g being acceleration due to gravity a greater than g m qa 10000000 b less than g

The position x of a particle w r t time t along x axis is given by x 9t t where x is in metre and t in second Find a Maximum speed along x direction b Position of turning point c Displacement in first ten seconds d Distance travelled in first ten seconds

A boy of mass 20 kg is standing on a 80 kg free to move long cart There is negligible friction between cart and ground Initially the body is standing 25 m from a wall If he walks 10 m on the cart towards the wall then the final distance of the boy from the wall will be 1 15 m 2013 3 15 5 m 2 12 5 m 4 17 m

Two balls a and b having momentum 10kg m s and 17kg m s respectively are moving towards each other along straight line assu ming there is no external force are acting on 2 balls the final momentum of the 2 balls af ter collision along the direction of ball a is

A proton of mass m and charge e is moving in a circular orbit in a magnetic field with kinetic energy 1 MeV The energy of a particle so that it can revolve in the path of same radius is 0 5 MeV O 1 MeV 2 MeV 4 MeV

A positively charged particle P crosses a region of uniform electric fie of intensity E Velocity u of the particle at the entry on the left side the region is perpendicular to the electric field as shown in the fir figure Speed of the particle at exit on the right side is U Now t experiment is repeated with a uniform magnetic field of induction superimposed on the electric field as shown in the second figure keepi entry velocity of the particle unchanged In this experiment speed of t particle at exit on the right side is U What can you conclude regard the speeds U and v d If u c If u B E B 9 then then U U U U If u d If u E B E B 2 2 then U U1 then U U

5 The wavelength of photon of energy E is same as moving with the 7 5 107 ms and kinetic energy the de Broglie wavelength of a material particle E E Then is

Two identical particles P and Q of rest mass m are moving with velocities 5c 2c and 19 5 in directions x and r respectively in the lab frame Calculate the energy of particle P in Q s rest frame b c 21654772E m c m c d m c

20 In potentiometer wire of length L and resistance 10 2 is connected in series with a battery of emf 2 5 V and a resistance in its primary circuit The null point corresponding to a cell of a emf 1 V is obtained at a distance If the resistance in the primary circuit is doubled then the position of new null point will be 1 0 6L 2 0 8L 3 4L 4 0 5L

According to the Bohr model the energy levels of a hydrogen atom can be found by making two assumptions i The electrons move in a circular orbit and ii The angular momentum of the electron in the 7 th th energy level is quantised to have a value The levels calculated with a nuclear charge Ze deals with a single electron in the orbit are called hydrogenic levels Assume that the two electrons in the ground state of a helium atom occupy the corresponding lowest hydrogenic level Now match Column I with Column II and select the correct option from the choices given below the column A The minimum repulsive energy between the two electrons would then be If for a hydrogen atom ionisation temperature is T the temperature at which he atoms ionise B C completely both electrons having left off the atom would be Energy required to remove two electrons from helium atom must be greater than A D Column I A 2 B 4 C 1 Your Answer A 1 B 4 C 3 A 1 B 3 C 2 A 2 B 3 C 1 Correct Answer Column 1 54 4 eV 2 27 Z eV 3 87 4 4T