Physics Questions

The stopping potential is 4 Vwhen wavelength of incident monochromatic radiation is If wavelength of incident radiation is doubled on same photosensitive material the stopping potential becomes V The threshold wavelength of the photosensitive material is Only one correct answer A B 100 D X C 3A X

An ordinary light is pass from a polaroid 41 sheet P Then after P another polaroid sheet P is placed then Intensity of light after P will be 2 1 remain same 2 half 3 Zero 4 Charge from zero to half of intensity of igad light unn

2 Two charges q and 3q are placed fixed on x axis separated by distance d Where should a third charge 2q be placed from q so that it will not experience any force q 1 3 d 3d 2 d 3d 2 d 2 4 d 3d 2 EEN PARK d 3d 2 NA

A wire of length is formed into a circular loop of one turn only and is suspended in a magnetic field B When a current I is passed through the loop the torque experienced by it is A 1 4n BIC B 1 4 IB C 1 4n B IC D 1 4 BI E 1 4m B I

Two point charges are placed at the corners of a rectangle of sides 5 00 cm and 10 0 cm as shown below The charges are q 8 00 C and q2 5 00 C Take V and U to be zero at infinity a What is the electric potential energy of the two charges b What is the electric potential at point A c What is the electric potential at point B d How much work is done by an external agent to move a 1 2 0 C charge from A to B 91

A block of mass M is connected to a spring of mass m and oscillates in simple harmonic motion on a horizon tal frictionless track The force constant of the spring is k and the equilibrium length is Assume that all portions of the spring oscillate in phase and that the velocity of a segment dx is proportional to the dis tance x from the fixed end that is vx x l v Also note that the mass of a segment of the spring is dm m l dx Find a the kinetic energy of the system when the block has a speed v and b the period of oscillation dx

n cells each of emfE and internal resistance r send the same current through an external resistance R whether the cells are connected in series or in parallel Then A R nr B R r C r nR D R nr E r nR

Four point charges 20 20 Q and Q are fixed on the vertices of a square whose sides have length L as shown in figure The point O is the intersection point of diagonals of the squa 2KQ fifth point charge 4Q is slowly moved from infinity to point O The work done by external agent during this process is av Write va in OMR sheet 1 20

Three concentric conducting shells A B and C of radius a 2a and 3a respectively are given charge Q 2Q and Q If potential of shell B 1 then value of N is 4 TEO K 3a NKQ is 6a 2Q Q Answer a 2a A B C

A source of frequency f is rotating in a circular path of radius R An observer in the same plane is also rotating in a circular path of radius 2R The centers of both circular paths are separated by 6R Both these are rotating with same angular velocity in same direction Find the difference between maximum and minimum frequency received by observer C is speed of

A man running on a horizontal road at 8 km h finds the rain falling vertically He increases his speed to 12 km h a finds that the drops make angle 30 with the vertical Find the velocity of the rain with respect to the road A 2 7 km h B 7 km h C 4 7 km h D 3 7 km h

The magnetic field at point P in the hollow cylindrical wire carrying a current i shown in the figure at a distance r from axis a r b is given by Taking current density to be uniform across its cross section 1 Moi r a 2 b a r a 12140 H 2 Moir 2 b a

What is the equivalent resistance of the circuit 2 3 4 Correct Answer 3 our Answer 2 Status incorrect 60 70 80 90 4V 12 20 HFww 402 ww V 202 www 202 ww

5 Three one over the other as shown in figure Find the minimum force needed to cause the motion in any part of the system Coefficient of friction is written for every surface on side C 0 4 0 3 0 1 B A 4 kg 6 kg 10 kg F

2 A photon of energy E ejects a photo electron from a metal surface whose work function is Po The electron then enters into an uniform magnetic field B in a direction perpendicular to the field It is observed that the electron describes a circular path Then calculate the radius r of the path a b c d eB O O O O A B 2M E Po eB 2M E Po eB O C D 2M Po E eB 2M o E

Four identical charges Q are fixed at the four corners of a square of side a The electric field at a point P located symmetrically at a distance a 2 from the cente of the square is 1 Q 2 2 80a 2 Q reva 3 2 20 Re0a 4 20 09

Five point charges each of value q are placed on five vertices of a regular hexagon of side L metre Wha is the magnitude of the force on a point charge of value q coulomb placed at the centre of the hexagon A 1 q 4 L B10 B 4 o L C 19 4t E L D 1 q 4 E L E zero

Board Competitive Exams 23 A wire of natural length Young s modulus Y and area of cross section A is extended by x Then the energy stored in the wires is given by 1 3 1 YA 21 1 YI 2 A 2 1 YA 31 1 YA 21

When the light source is kept 20 cm away from a photo cell the stopping potential is 0 6 V If the source is kept 40 cm away then the stopping potential will be 0 3 V 0 6 V O 1 2 V

Six forces lying in a plane and forming angles of 60 relative to one another are applied to the center of a homogenous sphere with a mass m 6 kg These forces are radially outward and consecutively 1N 2 N 3 N 4 N 5 N and 6 N The acceleration of the sphere is A B C zero 1 m s 1m s

A particle is thrown at an angle a sin in air as shown in the figure The angle received from the inside wate is water A 15 Only one correct answer B 45 C 30 F D 60 43

3 An n p n transistor is used in common emitter configuration as an amplifier with 1k2 load resistance Signal voltage of 10mV is applied across the base emitter This produces a 3m4 change in the collector current and 15u4 change in the base current of the amplifier The input resistance in kilo ohm is

When a metallic surface is illuminated by a light of frequency 8 10 4 Hz photoelectron of maximum energy 0 5eV is emitted When the same surface is illuminated by light of frequency 12 10 4 Hz photoelectron of maximum energy 2eV is emitted The work function is in eV

A sphere of radius R carries charge such that its volume charge density is proportional to the square of the distance from the center What is the ratio of the magnitude of the electric field at a distance 2R from the center to the magnitude of the electric field at a distance of R 2 from the center 1 1 2 2 3 4 4 8

A metallic wheel of radius and 8 spokes is rotated in a uniform magnetic field Bas shown The motional EMF across centre and rim is given by B X Only one correct answer A 4BPw B 2BPw C C 8BPw 1 R1 X

3 Given a uniform disc of mass M and radius R A small disc of radius R 2is cut from this disc in such a way that the distance between the centres of the two discs is R 2 Find the moment of inertia of the remaining disc about a diameter of the original disc perpendicular to the line connecting the centres of the two discs 1 3 32 MR 2 5 16 MR2 3 11 64 MR 4 None of these

The deformation beyond elastic limit is called plasticity A Strain is a dimensionless quantity R Strain is internal force per unit area of a body

In young s double slit experiment the central bright fringe can be identified 1 as it has greater intensity than the other bright fringe 2 as it is wider than the other bright fringes 3 as it is narrower than the other bright fringe 4 by using white light instead of

c The limits of visible spectrum are approximately 400nm to 700nm Find the angular width of the first order visible spectrum produced by a plane grating having 1500 lines per inch when light 2 Marks is incident normally on the grating

A coin is placed at the edge of a horizontal disc rotating about a vertical axis through its centre with a uniform angular speed 2 rads The radius of the disc is 50 cm Find the minimum coefficient of friction between disc and coin so that the coin does not slip g 10ms 2 1 0 1 2 0 2 3 0 3 4 0 4

rd Competitive Exams Mechanical Properties of Fluids 133 A cylinder of radius R full of liquid of density p is rotated about its axis at en rad s The increase in pressure at the centre of the cylinder will be Day R 2 R 2 pu R 2 2 30

A crane lowers a 134 kg box from rest with a force that varies with time as shown in the graph below Att 10s what is the velocity in m s of the box Be sure to include the appropriate sign in your answer Ft 0 10 5 10 t

Two particles A and B are projected simultaneously with speed of 20 2 m s and 20 m s from top of two building of height 60m and 80m as shown in figure Particle A is projected at an angle of 45 with the horizontal where as particle B is projected horizontally The distance between the building is 20 m Then find minimum distance between two particle A 4 5 m C 20 2 m B 12 5 m D 40 5 m 60m 2012m 45 d 20m 20m s 80m

Light of wavelength 5890 4 falls on a double slit arrangement having separati d 0 2mm A thin lens of focal length f 1m is placed near the slits The linear separation of fringes on a screen placed in the focal plane of the lens is 1 3 mm 4 1 mm 2 4 mm 3 2 mm

Figure shows LCR series ac circuit If L is removed from the circuit current leads voltage by 45 while if C removed current lags the voltage by 45 Current passing in the original circuit is R L wwwww HH Options 0 2 A O 1 5 A O 1 A O 0 5 A 1000 100V 200 Hz

L A can of mass 1 kg is thrown upward which reaches a height of h 25 m from the throwing position Calculate the work done by the gravitational force as the can reaches the highest point What is the change in kinetic energy of the can What is the change in potential energy of the earth can system

A solenoid has 2000 turns wound over a length of 0 3 m Its cross sectional area is equal to 1 2x10 m Around its central cross section a coil of 300 turns is wound If an initial current of 2 A flowing in the solenoid is reversed in 0 25 s the emf induced in the coil in mV is

If all the particles are moving with same velocity then maximum de Broglie wavelength will be for Neutron O Proton hr min B particle

Copper The work function for sodium and copper are 2 eV and 4 eV respectively Which of them is suitable for a photo cell with 4000 light Sodium Mark for Review Both 01 23 hr mi

errors percentage in the measurement of mass and speed are 2 and 3 respectively How much will be the maximum error in the estimation of kinetic energy obtained by measuring mass and speed 5 The a 11 c 5 b 8 d 1

Q4 of 90 Mark To reach your school at 10 30am let you start at 10 00am First you move 800m towards east then 600m towards north and finally 200m towards west Then net displacement is X

The nucleus 64Cu half life 12 7h is known to decay by electron capture 61 contribution to total decay rate and B decay 39 contribution to total decay rate Partial half lives for electron capture and decay respectively are Question Type Single Correct Type 1 2 3 20 8h 32 6h 28h 32 6h 61h 39h

Assuming earth is a smooth sphere of radius Re and mass Me If a particle is thrown horizontally tangentially from earth with half of escape velocity then find out maximum distance of particle from centre of earth and trajectory of particle in subsequent motion Question Type Single Correct Type 1 2 3 Re circular 8Re elliptical 4Re straight line

1 A grenade of mass 5M initially at rest explodes into two pieces of mass 3M and 2M and the masses travel in opposite direction with velocity 2V and 3V respectively Calculate the ratio of de Broglie wavelength of 3M to that of 2M a 2 3 b 3 2 c 9 4 d 1 O A O O B O C

9 Find the resultant of the following forces acting at point i 1 2 N along north east ii 9 8 2 N along north west iii 2 kg f along south Given g 9 8 m s 2 Ans 8 8 2 N along SW

A concavo convex lens of radii of curvatures 20 cm 10 cm respectively silvered on one side as shown then which of the following option is incorrect X O 3 If x 4cm then final is virtual enlarged 10 16 Silvered Surface 1 If x 8cm then final image coincide with object 2 If x 4cm then final image coincide with object lg 3 2 mi obiect is moving towards P then image is also moving towards P

If the momentum of a proton is changed by an amount Po the corresponding change in the de Broglie wavelength is found to be 0 25 Then the original momentum of proton was O Po hr mi 100Po

35 In the given arrangement of an experiment of a meter bridge if AC corresponding to null deflection of galvanometer is x what would be its value if radius of the wire AB is doubled THE a X A R www b 2x x C R www c 4 x B d 72

A body is projected from the ground for horizonta range 100 m At the highest point of its path breaks apart into two identical part P and Q If comes to rest then the horizontal distance of the point Q from the point of projection is 2 250 m 4 50 m 1 200 m 3 150 m

An object of mass 0 2kg executes simple harmonic motion along the x axis with a frequency of 25 Hz At the position x 0 04m the object has a kinetic energy of 0 5J and potential energy of 0 4J The amplitude of oscillation is 1 0 05m 2 0 06m 3 0 01m 4 none of these