Basic Physics Questions and Answers

Suppose that a 100 Watt beam of light is incident upon a metal surface If the light has a wavelength 200 nm how many photons strike the surface every second Hint Using the power of the beam find how much energy is incident upon the surface every second

constrained to move in a smooth circular slot of radius r in x y plane as shown in the figure The space is gravity free and the particle is initially at rest at 0 r Inner and outer surfaces of the slot are marked 1 and 2 respectively in the figure Let N and N represent normal reaction by surfaces 1 and 2 respectively on the particle Choose the correct answer 1 If a uniform magnetic field of strength B is applied along ve z direction and particle is imparted velocity v qBr in positive x direction 1 N 0 N 0 X qvB 2 N N 2 qVB 2 3 N qvB N O n

The value of de Broglie wavelength of an electron moving with a speed of 6 6 105 ms is approximately 1 Question Type Single Correct Type 1 2 3 11 111 211

he aim of studying the simple pendulum experiment To determine the frequency of the vibrating bob To determine the acceleration due to earth s gravitational To determine the time period of the vibrating bob All of the above

As shown in figure a convergent lens is placed inside a cell filled with liquid The lens has focal length 20 cm when in air and its material has refractive index 1 50 If the liquid has refractive index 1 60 the focal length of the system is 0 Question Type Single Correct Type 1 2 3 4 80 cm 80 cm 24 cm 160 cm

In the following circuit the amount of heat emitted by 150 resistance is 120 cal s The amount of heat emitted by 14 Q resistance will be in cal s 1 2 3 Question Type Single Correct Type 60 32 1402 28 E 1502 1602

28 Electric field between oppositely charged parallel conducting plates When two plane parallel conducting plates having the size and spacing as shown in the figure are given equal and opposite charges the field between and around them is approximately as shown while most of the charge accumulates at the opposite faces of the plates and the field is essentially uniform in the space between them there is a small quantity of charge on the outer surfaces of the plates and a certain spreadwing or fringing of the field at the edges of the plates As the plates are made larger and the distance between them diminished the fringing becomes relatively less This kind of arrangement is called capacitor Now if two plates are separated by a distance 3d and are maintained at a potential difference V then answer the following questions I i Capacitance of a parallel plate capacitor depends on a electric charge stored b electric field between the plates c potential difference applied d electrical permittivity of the medium between the plates ii If two protons are placed at points A and B respectively then which one will experience more force d A d B d a Proton at point A b Proton at point B c Proton at points A and B both experiences same force d None of the above 5 iii When both the protons are released then which one will gain more K E just before striking the negative ve plate a Proton released from point A b Proton released from point B c Proton released from points A and B will gain equal kinetic energy d No one will gain kinetic energy iv If one proton is moved from 1 A to B II B to C and III along ABCD then work done in cases I II and III respectively are a eED Zero eED b eED Zero Zero c eED eED Zero d eED eED Zero v Which property of electric field is shown by answer to III part of questions iv a Non conservative nature b Conservative nature c Dissipative nature

13 A porter lifts a heavy suitcase of mass 80 kg and at the destination lowers it down by a distance of 80 cm with a constant velocity Calculate the workdone by the porter in lowering the suitcase take g 9 8 ms 2 cions 1 784 0 J 2 627 2 J 3 627 2 J 627200 I

A convex lens A of focal length 20 cm and a concave lens B of focal length 10 cm are kept along the same axis with a distance d between them If a parallel beam of light falling on A leaves B as a parallel beam then d is 10 cm 20 cm 30 cm 15 cm

A linear harmonic oscillator of force constant 6 x 105 N m and amplitude 4 cm has a tota energy 600 J Select the correct statement 1 Maximum potential energy is 600 J 2 Maximum kinetic energy is 480 J 600 1

If the system shown in fig is in equilibrium then value of T is g 10 m s 1 2 Question Type Single Correct Type 300 N T 3 400 N 30kg T 2 40kg

1 Outside when electric field E is perpendicular to delta S then electric flux is zero and when they are parallel to each other then electric flux is maximum 2 inside when electric field E is perpendicular to delta S then electric flux is maximum and when they are parallel to each other

If light travels a distance x in t sec in air and 10x distance in t2 sec in a medium the critical angle of the medium will be Question Type Single Correct Type 1 2 3 tan sin 1 sin 1 12 101 10t

A block of mass m 4 kg is placed over a rough inclined plane as shown in figure The coefficient of friction between the block and the plane is 0 6 A force F 10 N is applied on the block at an angle of 30 The contact force between the block and the plane is 45 2 12 X is 1 27 15 N 30 FO 3 we ke 2 x xx th EX N 40 2 16 32 N

3 A short bar magnet of magnetic moment 0 5 J T is placed with its magnetic axis in the magnetic meri dian with its north pole pointing geographical north A neutral point is obtained at a distance of 0 1 m from the centre of the magnet Find the horizontal compo nent of the earth s magnetic field Ane 103T

VVV are the velocities of rain wind and man are given in column IV in column II match column I with column II m 111 Column I a V 5j V 5i V 0 b V 5j V 5i Vm 5i c V 5j V 5i 5j V Si 5i W m d V 5 j V 5i 5j V 5i A a q p b q c r d r s C a qp b q s c r d r s Column II p V 10j q V 5i 5j 1 V 5j s V 10i 10j B a q b p r c p r d s D a q b r c p d s

Two radio active substances A and B have decay constant 5 and respectively At t 0 they have the same number of active nuclei The ratio of number of active nuclei of A to those of B will be 1 e after a time interval Question Type Single Correct Type 1 2 3 4 2 1 2A

displaces the object from 2 3i j 2k Calcul OPTIONS MARE

30 A moving particle has the coordinates x 16 t and y 16 t at any instant t Find the resultant velocity of the particle at t 3 seconds OS A 202 19 m s B 096 m s C D 101 19 m s 300 m s

27 Charges can neither be created nor destroyed it can be transferred from one place to another The force between two charges are given by coulomb s law To find the force acting on a unit positive test charge electric field is calculated due to that charge The electric field always originates from ve charge and ends on ve charge Electromagnetic waves can be generated that transported energy i Does Coulomb s law agree with Newton s 3rd law a No b Yes c May be d Can t say ii What is the inherent characteristic of matter a Charge is inherent characteristic b Quantization of charges c Coulomb s law is not applicable in vacuum d None of the above iii Are electric field E and force F vector or scalar quantity a E is vector quantity and F is scalar b E and F are vector quantity c E is scalar F is vector d E and F is scalar iv Can Coulomb s law be used to define unit of charge a Yes b No c May be d Can t comment v Is physical significance of EM field useful in electrostatics a Yes b No c May be 5

Velocity of three particles A B and C varies with time at as v 2t 6 m s v 3 4 m s and c 61 4t m s Match the following table for pseudo force Column I Column II a On A as observed byB b On B as observed by C c On A as observed by C d On C as obsreved by A A a r b r c r d q C a t b r c r d q p Along positive x direction q Along negative x direction r Along positive y direction s Along negative y direction t zero B a t b r c q d q D a t b r c r d r

5 A conducting rod of length 2 m is placed on a hori zontal table in north south direction It carries a current of 5 A from south to north Find the direction and magnitude of the magnetic force acting on the rod Given that the Earth s magnetic field at the place is 0 6x10 4T and angle of dip is T

3 ML Which of the following relation cannot be deduced using dimensional analysis the symbols have their usual meanings 1 y A sin ot kx 2 v u at mv 3 k 4 All of these

The variation of magnetic susceptibility X with temperature for a diamagnetic substance is best represented by figure X X X T T T

In the figure shown ABCD is a rectangular smooth tube kept fixed in a vertical plane A particle is projected from point A to reach point C with same speed for both paths ADC and ABC At the corners B and D velocity changes its direction by 90 without any change of its magnitude at that corner If time taken on paths ABC and ADC are t and t respectively then given b A t t A b B B t t C t t D none of these

A particle is projected with a velocity whose horizontal and vertical components are u and v If A and B are the points on its trajectory at the same height h above the point of projection distance AB is A 2u g 1 2 2gh B 2u 2gh 2uv g D 2u 2gh

2 2 A force vector applied on a mass is represented as F 61 8j 10k N and accelerates the mass at 1 m s The mass of the body is 2 C 1 10 kg 3 2 10 kg 2 20 kg 4 10 2 kg

50 Which of the following are correct a x 2x 6x 2 0 has exactly four real solution b x5 5x 10 has exactly three real solutions c x ax b 0 where n is an even natural number has atmost two real solution a d x 3x c 0 c 0 has two real solution for x 0 1

A satellite revolves round the earth in an elliptic orbit it s speed will be 1 Is the same at all points of the orbit 2 Is the greatest when it is closest to the earth 3 Is the greatest when it is farthest from the earth 4 Depends upon the mass of the earth

A car is moving with uniform acceleration along a straight line between two points X and Y Its speed at X and Y are 2m s and 14m s Then A Its speed at mid point of XY is 15m s B Its speed at a point A such that XA AY 1 3 is 5m s C The time to go form X to the midpoint of XY is double of that to go from mid point to Y D The distance travel in first half of the total time is half of the distance travelled in the second half of the time

A pair of adjacent coils has a mutual inductance of 1 5 H If the current in one coil changes from 0 to 20 A in 0 5 s what is the change of flux linkage with the other coil 30 Wb 33 Wb 23 Wb 42 Wb

3 Q 3 The kg displacements of a particle depends on time t according to the following relation S t t t The velocity and displacement 3 of the particle at the instant when its acceleration is zero are respectively 1 2 0 4 None of the above 1 0 3 Him 1 3 3 3

infinitely long straight wire carrying current I 4A as shown in figure What will be the total magnetic flux crossing through the rectangular loop I 0 531 Wb 0 324 Wb 4 m B A 2 m C 2 m D

A fighter plane flying horizontally at an altitude of 1 5km with a speed 720kmh passes an anticraf directly The shot is fired at an angle 19 5 with the vertical to strike the plane sin 19 5 3 Then A The muzzle velocity required is 587m s B The muzzle velocity required if 600m s C To avoid hitting the plane the piolot should fly it at a minimum altitude of 16km D To avoid hitting the plane the piolet should fly it at a minimum attitude of 15 5km

The period of oscillation of a freely suspended thin bar magnet is 4 sec If it is cut into two equal parts along the length then the time period of each part will be 4 sec 2 sec 0 5 sec 0 25 sec

A vibration magnetometer placed in magneti meridian has a small bar magnet The magne executes oscillations with a time period of 2 se in earth s horizontal magnetic field c 24 microtesla When a horizontal field c o 18 microtesla is produced opposite to the earth field by placing a current carrying wire the ne time period of magnet will be 1 4s 2 1s 3 2s 4 3s

A boy is standing in a lift moving upwards with constant acceleration The boy throws a ball vertically up with initial velocity u with respect to the lift and it reaches his hand just after time t The upward acceleration of the lift IS P P

In a permanent magnet at room temperature Magnetic moment of each molecule is zero The individual molecules have non zero magnetic moment which are all perfectly aligned Domains are partially aligned All domains are perfectly aligned

In a permanent magnet at room temperature O Magnetic moment of each molecule is zero The individual molecules have non zero O magnetic moment which are all perfectly aligned O Domains are partially aligned All domains are perfectly aligned

Vertical displacement of a plank with a body of mass m on it is varying according to law y sin wt 3cos wt The minimum value of w for which the mass just breaks off the plank y is positive vertically upwards Question Type Single Correct Type 1 g 4

The moment of a magnet 15 cm 2 cm 1 cm is 1 2 A m What is its intensity of magnetisation 4 x 10 4 Am 4 104 Am 1 O 2x 104 Am 1 104 Am

At the initial moment three points A B and C are on a horizontal straight line at equal distances from one another Point A begins to move vertically upward with constant velocity v and point C vertically down ward without any initial velocity at constant acceleration a Assuming the points begin to move simulta neously then for all the points to be constantly on one straight line the point B moves with A acceleration and initial velocity v both upward 1 2 1 B initial velocity upward and acceleration a downward C zero acceleration and intial velocity v downward

Consider a dipole placed in a uniform electric field E as shown The charged particles are connected by a light rigid rod Under influence of the uniform electric field frequency of small oscillations of the dipole would be 2x 8 AqE Bm 2m pa Find the value of fB Write an answer

The magnetic susceptibility of paramagnetic material at 73 C is 0 0075 its value at 173 C will be O 0 0045 O 0 0030 O 0 015

Which of the following are corret A Average speed of a particle in a given time is never less than the magnitude of the average velocity dv B It is possible to have a situation in which dt Obut d 0 C The average velocity of a particle is zero in a time interval It is possible that the instantaneous velocity is never zero in the time interval D The average velocity of a particle moving on a straight line is zero in time interval It is possible that the

A ferromagnetic material is placed in an external weak magnetic field the magnetic domains O Increase in size O Decrease in size O May increase or decrease in size O No relation

Max Schon as a will I MIT 3 A parallel beam of white light falls normally on a single slit 0 320 mm wide and 1 m behind this slit a small spectroscope is used to explore the spectrum of the diffracted light Predict if you can what will be seen in the spectroscope if the slit is displaced in a direction perpendicular to the diffracting slit by a distance of 1 250 cm from the axis 1 111t

BOTANY 3 7 A force of 3 4 5k N acts on a body for 2 seconds and produces a displacement of 1 24m Calculate the power OPTIONS MARK FOR REVIEW CLEAR SELECTION A 7W OB 14 W C 9W

A rectangular plate of mass 20 kg is suspended from points A and B as shown If the point B is suddenly removed determine the angular acceleration in rad s of the plate A 0 2 m B 0 15 m Rate this question

Question No 4 One of two rings with radius r 1m is at rest and the other moves at velocity y 5 3 m s towards the first one Find the velocity in m s of the upper point of intersection when a 1 m where a is the distance between centres of two rings 18