Basic Physics Questions and Answers

of these 0 By using a concave mirror image of a distant tree is focussed on a screen The distance between the screen and the mirror is A Equal to twice the focal length of the concave mirror B Equal to one fourth of the focal length of the concave mirror C Equal to half the radius of curvature of the concave mirror D Equal to the radius of curvature of the concave mirror E None of these

18 A copper rod length L and radius r is suspended from the ceilling by one of its ends What will be elongation of the rod due to its own weight when p and Y are the density and Young s modulus of the copper respectively 1 se 3 p gL 2Y Y Fl p g L 2Y V ADQ mgl AY 2 4 Dl FI Ay S M pgL 2Y pgL 2Y f mg M SYV Axe De Sx xl x g Dexy

Find its vertical component on a particle along a direction making an angle of 60 with vertical Find the resultant force of the forces 30 N due East 20 N due North 50 N due West and 40 N due South which are acting simultaneously upon a particle If a 21 31 6 61 21 3k and c i k then find a 3a 2b c

A man pushes a sled across the snow using a force of 300 N over a distance of 2 m What is the kinetic energy of the sled after he pushes it Assume there is no friction A 600 J OB 1200 J OC 300 J OD 150 J

Ex 19 N molecules each of mass m of gas A and 2N molecules each of mass 2m of gas B are contained in the same vessel at temperature T The mean square of the velocity of molecules of gas B is v and the mean square of x component of the velocity of molecules of gas A is w The ratio 24 W v a 1 is b 2 c d 3 2 3

U2 The load A is being pulled with the help of two inextensible strings th pass over two fixed pulleys as shown in the figure At an insta velocities of the ends of the string being pulled are u and uz and angle between the strings connected to the load is 0 what is speed of

A monkey of mass 20 kg rides on a 40 kg trolley moving at a constant speed of 8 m s along a horizontal track Frictional force can be neglected If the monkey jumps vertically with respect to the moving trolley to catch the hanging branch of tree the speed of the trolley after the monkey has jumped off is Question Type Single Correct Type 1 2 3 4 16m s 12m s 8m s 6m s

2 13 A uniform disc of mass M and radius R is supported vertically by a pivot at its periphery as shown A particle of mass M is fixed to the rim and raised to highest point above the centre The system is released from rest and it can rotate about pivot freely The angular speed of system when it attached object is directly beneath the pivot is M 1 3 48g V19R 48 g 2 4 24 8 19 R 24 8 8

The figure below shows a portion of spectrum containing several digital TV channels VBW 30 000000 kHz Ref 20 000 dBm Div 10 0 RBW 30 000000 kHz Atten Auto 40 00 60 00 80 00 100 00 120 00 Start 640 000000 MHz Level A Level B Center 665 000000 MHz Span 50 000000 MHz Estimate the bandwidth of each channel Give your answer to the nearest MHz Stop 690 000000 MHz Swp Time 520ms 6500 pts

For the triangle shown in the figure below what are each of the following Let y 84 0 m and r 85 0 m Assume the triangle is a right triangl le a the length of the unknown side x m b the tangent of 0 c the sin of

Q6 A police van moving on a highway with a speed of 30 km h fires a bullet at a thief s car speeding away in the same direction with a speed of 192 km h If the muzzle speed of the bullet is 150 m s with what speed does the bullet hit the thief s car O A 105 m s O 8 110 m s O C 120 m s O D 100 m s

3 Consider the shown diagram All pulleys are massless and frictionless springs are ideal and all connecting strings are ideal Find the natural frequency of the system shown in figure 1 f 3 f k 1 16k 2 V m 1 k 2 V9m of S mmmm 2k m 2 f 4 f 16 k4n 40 1 16k 2 V 9m 1 4k 2TV9m 16kn

2m are placed on a fixed triangular wedge by means of a massless inextensible string and a frictionless pulley as shown in figure The wedge is inclined at 45 to the horizontal on both the sides If the coefficient of friction between the block A and the wedge is 2 3 and that between the block B and the wedge is 1 3 and both the blocks A and B are released from rest the acceleration of A will be a

8 Two charges 4 cm apart repel each other with a force of 2x 10 2 N in air When a dielectric slab of thickness 1 cm is placed between them the force is reduced to 1 5x 102 N Calculate the permittivity of the dielectric

Find the amount of work done to increase the temperature of one mole of ideal gas by 30 C if it is expanding und the condition Voc T25 R 8 31 J mol K 1 16 62 J 2 166 2 J 3 1662 J 4 1 662 J constant The bulk modulus

Statement A Ability to do the work is called energy Statement B Energy and power is a scalar quantity Both A and B are correct Both A and B are incorrect A is correct and B is incorrect A is incorrect and B is correct

A solid sphere of mass M and radius R is pulled by a force F as shown in figure If the sphere does not slip over the surface then frictional force acting on the sphere is m 2F Marks 4 00 1 00 Rough

When photon of frequency v falls on metal plate of work function do the photoelectrons of maximum kinetic energy k are ejected If the frequency of radiation is tripled the maximum kinetic energy of the ejected electrons will be 1 k po 3 3k 200 2 k 2hv 4 both 2 3

A force vector applied on a mass is represented as F 61 8 10k N and then mass accelerates with 1 m s2 What will be the mass of the body 1 2 the direction of A Let A cos 0 1 sin 0 be any vector What will be the unit vector i in 2

3 A student plotted the following four graphs representing the variation of velocity of sound v in a gas with the pressure Pat a given temperature Which one is correct A E None of these P B P C P D

A hammer weighing 2 5 kg moving with a speed of 1 m s strikes the head of a nail driving it 10 cm into a wal The acceleration of the nail and the impulse imparted to the wall will respectively be A 5 m s 2 2 5 N s C 7 5 m s 2 3 5 N s D 6 m s 2 4 Ns E None of these Which of the following correctly depicts reflection in case of plane mirrors inclined at 40 B 10 m s 2 5 NS

A solid conducting sphere of radius a has a net positive charge 2Q A conducting spherical shell of inner radius b and outer radius c is concentric with the solid sphere and has a net charge Q The surface charge density on the inner and outer surfaces of the spherical shell will be Question Type Single Correct Type 2Q C Q

4 In a nuclear fusion reaction two nuclei A and B fuse to produce a nucleus C releasing an amount of energy AE in the process If mass defects of A B and C nuclei are Am AmB and Amc respectively then correct relation among the following is 1 AmA AMB Amc 2 AMA AMB Am 3 AmA AmB Amc 4 AMA AMB Amc AE AE EEN PA

59 A uniform wire of length L diameter D and density p is stretched under a tension T The correct relation between its fundamental frequency f the length L and the diameter Dis 1 LD c f 1 1 2 D b fo d f 1 LAD 1 LD

18 The charge distribution inside a sphere of radius R 2a b is given by the volume charge densit p ar br where a and b are constants and r is the radial distance from the center of the sphere At what distance from the center of the sphere will the electric field go to zero

Two particles rotating on a circle have the time period 10 minute and 12 minute respectively They start simultaneously from same point in the same direction After how much time will they meet again 1 50 minute inut 2 1 hour hour 10 minute

one Optics When interference of light takes place a energy is created in the region of maximum intensity b energy is destroyed in the region of maximum intensity c conservation of energy holds good and energy is redistributed d conservation of energy does not hold good 40 Two slits are made one millimeter apart and the screen is placed one metre away The fringe separation when blue green light of wavelength 500 nm is used is a 5 x 10 m c 2x 10 m b 2 5x 10 m d 10 x 10 m 41 In Young s double slit experiment light waves of wavelength 5 4 x 10 nm and 68 5 x 10 nm are used in turn keeping the same geometry of the set up The ratio of the fringe widths in two cases is c 7 9 b 4 3 d 9 5 42 The fringe width in a Young s double slit interference pattern is 2 4 x 10 m when red light of wavelength 6400 is used How much will it change if blue light of wavelength 4000 is used a 9 x 10 m c 4 5 x 10 m b 0 9 x 10 m d 0 45 x 10 m a 0 1 mm c 4 3 mm 43 In a double slit experiment the distance between slits is increased ten times whereas their distance from screen is halved then the fringe width is a becomes b becomes 90 a 0 19 Dand 0 33 D b 0 19 Dand 0 55 D c 0 33 Dand 0 65 D d 0 33 Dand 0 75 D b 0 5 mm d Imm 46 Interference fringes were produced in Young s double slit experiment using light of wavelength 5000 A When a film of material 2 5 x 10 cm thick was placed over one of the slits the fringe pattern shifted by a distance equal to 20 fringe widths The refractive index of the material of the film is a 1 25 b 1 33 c 1 4 d 1 5 20 c it remains same d becomes 10 44 Yellow light of wavelength 6000 A produces fringes of width 0 8 mm in Young s double slit experiment If the source is replaced by another monochromatic source of wavelength 7500 and the separation between the slits is doubled then the fringe width becomes Screen 47 In a two slit experiment with monochromatic light fringes are obtained on a screen placed at some distance from the plane of slits If the screen is moved by 5 x 102 m towards the slits the change in fringe width is 3 x 10 m If the distance between slits is 10 m the wavelength of light will be a 3000 A c 6000 A 229 48 In a Young s double slit experiment an electron beam is used to obtain interference pattern If the speed of electron decreases then a distance between two consecutive fringes remains the same b distance between two consecutive fringes decreases c distance between two consecutive fringes increases d none of these 45 A small transparent slab containing material of p 1 5 is placed along AS as shown in figure What will be the distance from O of the principal maxima and of the first minima on either side of the principal maxima obtained in the absence of the glass slab AC CO D S C S C d D b 4000 A d 7000 A 49 In a double slit interference pattern the first maxima for infrared light would be a at the same place as the first maxima for green light b closer to the centre than the first maxima for green light c farther from the centre than the first maxima for green light d infrared light does not produce an interference pattern 50 In a double slit experiment using light of wavelength 600 nm the angular width of a fringe on a distant screen is 0 1 The spacing between the two slits is

4 0 5 33 A wave y A sin t x v is travelling along a string It undergoes reflection and the reflected wave is y A sin t x v If the superpose then what is correct a Only stationary wave is formed b Stationary and propressive both waves are formed c Max amplitude of stationary wave is A d Max amplitude of stationary waves is 2A 1 a d 2 a b d 3 b d 4 b c 33 y Tada A sin t x v 00 any A sin t x v 1 a d 2 a b d 3 b d 4 b c a b c d 44 2

A molecule of water appear as shown in figure Its dipole moment assuming that al the electrons in the molecule rotate symmetrically about the oxygen nucleus is nearly Take cos 52 0 616 0 OK 104 H 1 x 10 1 Cm 2 10 2 Cm 2 10 Cm d 0 96x10 10 m H

by a belt Two wheels are connected The radius of larger wheel is three times that of the smaller one What is the ratio of the rotational inertia of larger wheel to the smaller wheel when both wheels have same angular momentum

ngular connector PQ of length I and resistance R and it is moving with a speed v as shown in figure The set up is placed in uniform magnetic field going into the plane of the paper The three currents I1 I2 and I are

A rectangular opening on the side of a tank has a width The top of the opening is at a depth h below the surface of the water and the bottom is at a depth h Figure The volume of water that emerges from the opening in a unit time is given by a 2g m s Fill the value of a in OMR sheet 3 Given h 1m h 4m and m

6 The period of oscillation of a simple pendulum is T 2 L g Measured value of L is 10 cm known to 1 mm accuracy and time for 100 oscillations of the pendulum is found to be 50 s using a wrist watch of 1 s resolution What is the accuracy in the determination of g a 2 201 b 3 d 5 c 4

Two right angled prisms having the same refracting angle 60 are placed as shown in the figure A ray of light incident on the first prism is finally deviated by an angles 90 grazingly as shown The refractive index of second prism is 2 The refractive index the first prism is equal to THE NAR A 2 sin 30 Mi 60 B sin 45 in 60 60 30 30 60 A GROUP C 2 sin 15 in 60 D 2 sin 60 i 200

Flow of electrons through a wire is known as current Battery has to do a work for this Then work done by the battery in sending five hundred electrons through the resistor R in given circuit diagram is A 1 44 x 10 3 J C 1 44 x 10 5 J B 4 8 x 10 6 J D 4 8 x 10 6 J www IR LAHL 12V B 6

A bomb explodes in mid air when it has horizontal velocity of 20 ms 1 It breaks into tv pieces A and B having masses in ratio 1 2 If goes vertically at speed 80 ms 1 the speed of will be 1 40 ms 1 2 50 ms 1 3 60 ms 1 4 100 ms

a The pumping mechanism used in a Ruby laser is b The refractive index of the core is than that of the cladding c A hologram contains the information of the object in both and d A hologram is the result of interference of and beams e The hologram acts as a in the reconstruction process

What should be the displacement of a simple pendulum whose amplitude is A at which potential energy is 4th of the total energy Question Type Single Correct Type 1 2 A 2 A 2

A projectile is projected with velocity kve in vertically upward direction from the ground into the space ve is escape velocity and k 1 If air resistance is considered to be negligible then the maximum height from the centre of earth to which it can go will be R radius of earth O O O R k 1 R k 1 R 1 k R k 1

243 Bromine with atomic mass 79 942 u is composed of nearly equal amounts of two isotopes one of which contains 79 nucleons per atom The mass number of the other isotope is O A 78 O B 80 O 79 O D 81

Proton with kinetic energy of 1 MeV moves from south to north It gets an acceleration of 1012 m s by an applied magnetic field west to east Th value of magnetic field Rest mass of proton is 1 6 x 10 27 kg mT Approximate the answer to two decimal places

A source and an observer move away from each other with a velocity of 10m s with respect to ground If the observer finds the frequency of sound coming from the source as 1950 Hz then original frequency of source is velocity of sound in air 340 m s 2001 a 1950 Hz c 2132 Hz b d 2068 Hz 2486 Hz

The maximum electric field at a point on the axis of a uniformly charged ring is Eo At how many points on the axis will the magnitude of the electric filed be E 2 Choose only 1 answer A 1 Your Answer

A narrow beam of X rays with wavelength 1 5 A is reflected from an ionic crystal with an fcc lattice structure with a density of 3 32 gcm The molecular weight is 108 amu 1amu 1 66 10 24 g A The lattice constant is a 6 00 A 0 b 4 56 A 0 c 4 00 A d 2 56 A

Three charged particles are in equilibrium under their electrostatic forces only Question Type Single Correct Type 1 2 3 A The particles must be collinear All the charges cannot have the same magnitude All the charges cannot have the same sign The equilibrium is unstable

In figure is shown a system of four capacitors connecte across a 10 V battery Charge that will flow from switch when it is closed is 2015 Online 2 F H HH 3 F a 5 uC from b to a a S b 10 V 3 F HH 4 2 F b 20 C from a to b

84 If the angle between the pass axis of the polarizer 92 and the analyzer is 45 the ratio of the intensities of original light and the transmitted light after passing through the analyzer is a 1 b c I d 93 At w from a An u at ar Ther

On a hypothetical planet when a ball is thrown vertically up with speed u from the top of a tower of height H it takes 18 second to reach the ground If the same ball is thrown down with same speed u from there it takes 8 seconds to come down Now if the same ball is released from rest from the tower top the time taken by it to reach the ground is 1 13 second 2 12 second 3 14 second 4 11 second

A hollow steel sphere weighing 200 kg is floating on water A weight of 10 kg is to be placed on it in order to just submerge it at a temperature of 20 C Now the weight that should be decreased when temperature increases to 25 C is water 1 5 x 10 C a 1 x 10 C el R 200 kg steel 10 kg HR Tafell

car is moving with speed 30 ms on a circular path of radius 500 m Its speed is increasing 1 rate of 2 ms what is the acceleration of the car B 2 7 ms 2 2 A 2 ms D 9 82 ms2 C 1 82 ms