Basic Physics Questions and Answers

A rope is hanging vertically with its two ends fixed to walls at same horizontal level as shown Tension at the bottom most point is 90N If the mass unit length of rope is 4 kg m find radius of curvature in metres at point C Take g 10 m s 30 C

A ball is thrown upwards from the foot of a tower The ball crosses the top of the tower twice after an interval of 4 second and the ball reaches ground after 8seconds then the height of tower in meters is A 20 m B 30 m LOS 60 m Le D 50 m A ball is thrown upward from the edge of a cliff 20

x 4 The equation of a wave is given by Y A sin x are in metre The dimension of and A are 1 L and L 2 and L 3 L and T 4 L and T Ye y and 4 fa Y A sin sin 2x y L 1 L 2 L 3 L T 4 L T lx X A I go

1 AL In the figure shown here a point object O is placed in air A spherical boundary separtes various media of radius of curvature 2 0 m AB is the principal axis The refractive index above AB is 1 6 and below AB is 2 0 The separation between the images formed due to refraction at spherical surface is 1 zero 3 12 m A O 2m 1 6 B u 2 0 2 infinity 4 10m

If three forces F 6ai 8aj N F 8bi 3bj N and F3 261 19 N acting simultaneously on a body keep it in translational equilibrium Net force 0 determine numerical value of 0 5 a b

Q13 In Young s double slit experiment waves from two slits have path difference of i 0 ii N4 The corresponding ratio of intensities at two points on a screen are O A 1 8 4 O B 4 11 2 O C i 4 i 28 O D 1 2 ii 4

t 45 Given that Y A sin P qx where t represents time in 45 second and x represnts distance in meter p and q are constant which of the following statements is true The unit of t is same as that of q 2 The unit of x is same as that of p 3 The unit of x is same as that of q 4 The unit of t is same as that of p Y A sin y A sin paq fi 1 t 2 X 3 X 4 t p P q p qx t P T qx 9 2 1

A beaker is filled with water to a height of 12 5 m The apparent depth of the needle lying the bottom of the tank as measured by a microscope is 9 4 cm What is the refractive inde of water If water is replaced by a liquid of refractive index 1 63 upto the same height what distance would the microscope be moved to focus on the needle again

Mrical If H calories are generated on doing work W and if by H calories amount of work done is W which of following is the correct relation 1 W H constant 4 None of the above 3 WH constant 2 W H constant 10m The wheel disturbs a mass of 2kg wa

Three particles each of mass m are placed at the corners of equilateral triangle of side 18 2 Which of the following is lare correct 1 Moment of inertia about axis 1 is 2 Moment of inertia about axis 2 is 5 ml 4 3 2 m m 4 N 18 3 Moment of inertia about an axis passing through one corner and perpendicular to the plane is 2m 4 All of these

136 of 103 Wb passes through B no current through B If no current passes through A and a current of 2 A passes through B then the flux through A is a 5 x 10 Wb b 4x10Wb c 5 10 Wb d 2 x 10 Wb 65 A pair of adjacent coils has a mutual inductance of 2 5 H If the current in one coil changes from 0 to 40 A in 0 8 s then the change in flux linked with the other coil is a 100 Wb c 200 Wb b 120 Wb d 250 Wb 66 If number of turns in primary and secondary coils is increased to two times each the mutual inductance a becomes 4 times b becomes 2 times c becomes times d remains unchanged a Honb n n L b Hona n n 1 c Mona n n L d Honb n n L 68 A 2 m long solenoid with diameter 2 cm and 2000 turns has a secondary coil of 1000 turns wound closely near its midpoint The mutual inductance between the two coils is a 2 4 x 10 H c 1 28 x 10 H b 3 9x 10 H d 3 14 10 H 69 A solenoid of length 30 cm with 10 turns per centimetre and area of cross section 40 cm completely surrounds another co axial solenoid of same length area of cross section 20 cm with 40 turns per centimetre The mutual inductance of the system is a 10 H c 3 mH b 8 H d 30 mH a 7 54 H c 9 54 H 71 Two conducting circular loops of radii R and are placed in the same plane with their cent coinciding If R R the mutual inductance between them will be directly proportional to a R R b c 2 2012 2n L a 72 A small square loop of wire of side I is placed inside a large square loop of wire of side L The loop are coplanar and their centres coincide What is the mutual inductance of the system a 2 2 Ho 12 of Wb A is a self inductance c magnetic flux mtG Objective NCERT P b 8 54 H d 10 54 H R R 67 A short solenoid of radius a number of turns per unit length and length L is kept coaxially inside a 73 The physical quantity which is measured in the unit very long solenoid of radius b number of turns per unit length n What is the mutual inductance of the system a 4 H c 3 H c b b 8 2 H1 TL 2 40 120 RL R R d 2 22 al 74 Two coils have self inductance L 4 mH and L 1 mH respectively The currents in the two cos are increased at the same rate At a certain instant of time both coils are given the same power If I and I are the currents in the two coils at that instant of time respectively then the value of b mutual inductance d both a and b b 2 H d 6 H d d 1 75 In a coil current falls from 5 A to 0 A in 0 2 s If an average emf of 150 V is induced then the self inductance of the coil is b N d N i 1 is 76 If N is the number of turns in a coil the value of self inductance varies as a no c increased by a increasing its area of cross section increasing its length b c increasing the current through it d increasing the number of turns in it 70 A circular coil with a cross sectional area of 4 cm has 10 turns It is placed at the centre of a long solenoid that has 15 turns cm and a cross sectional area of 10 cm as shown in the figure The axis of the 77 The self inductance of a long solenoid cannot be coil coincides with the axis of the solenoid What is their mutual inductance

A heavy brass sphere is hung from a spring and it executes vertical vibrations with period T The sphere is now immersed in a non viscous liquid with a density 1 10 th that of brass When set into vertical vibrations with the sphere remaining inside liquid all the time the time period will be 1 9 10T 3 9 10 T 2 10 9T 4 unchanged

In the Young s double slit experiment with sodium light The slits are 0 589 m apart The angular separation of the third maximum from the central maximum will be given 589 nm 1 sin 0 33 108 2 sin 0 33 10 6 sin 3 x 10 6 3 sin 3 10 8 4

Two pendulums of time periods 3s and 7s respectively start oscillating simultaneously from two opposite extreme positions After how much time they will be in phase 1 3 21 8 21 2 S S 21 2 S 4 21 s S 10

14 Four identical ball bearings in contact with each other and resting on a frictionless surface are hit head on by other two identical ball bearings as shown Then the possible outcome s may be Vo 1 11 14 100 2v 00000 8 v oooo Oooo Vo SIN oooo 2 Only 11

A bee is at position 21 41 3k m at t 0 It moves with a constant velocity v 31 41 m s for two seconds Final position of the bee is T ai bj ck m at t 2s Find the value of b a c

4 A thin metal dise of radius R is charged and carries a total electric charge of Q Find the surfac charge density o r r is the distance from the center of the disce in the plane of the disc a r R b d exp r R

69 A solenoid of length 30 cm with 10 turns per centimetre and area of cross section 40 cm completely surrounds another co axial solenoid of same length area of cross section 20 cm with 40 turns per centimetre The mutual inductance of the system is a 10 H c 3 mH 70 A circular coil with a cross sectional area of 4 cm b 8 H d 30 mH 75 D in c 76 If se

A boy on level ground watches a hot air balloon launched from a point 18 0 m away from him The balloon rises with constant speed 0 314 m s Find the rate at which the angle of elevation of the balloon at his eye is changing when the angle becomes 60 0 degrees A 2 0 degree sec C 0 25 degree sec B 1 0 degree sec D 0 15 degree sec

Two objects are placed at a distance of 100 m from a person The diameter of the eye lens of the person is 2 mm What should be the separation between the objects so that they can be seen just resolved The wavelength of light is 5000 A 1 1 cm 2 1 5 cm 3 2 cm 4 3 cm

Diameter of the objective of a telescope is 200 cm What is the resolving power of a telescope Take wavelength of light 5000 A A 1 x 106 B C skipped 6 56 x 106 3 28 106

11 Consider the situation shown in figure Water H is filled in a beaker upto a height of 10 cm A plane mirror is fixed at a height of 5 cm from the surface of water Distance of image from the mirror after reflection from it of an object O at the bottom of the beaker is A 15 cm B 12 5 cm C 7 5 cm D 10 cm 1

Negative Marks A 25 N force is applied to the block as shown in figure Choose the CORRECT option if initial velocity of block is zero Take g 10 m s Normal contact force is 10N Friction force is 8N O Friction force is 10N O Block is in equilibrium 37 25N 2kg P0 5 HF 0 4

Consider the following statements about the blocks shown in the diagram that are being pushed by a constant force on a frictionless table i All All blocks move with the same acceleration ii The net force on each block is the same F 3 kg 2 kg 1 kg Which of these statements are is correct A i only B ii only Roth li

Boy A is standing at a point 3m west and 4m south to boy B Assume the east and the north towards the positive x and y axis of coordinate system Boy A starts moving along a vector a 1 51 21 with a constant speed of 2 m s of 5s and stops Now how far in meters in the boy A from the boy B

Velocity vo is such that spheres are at minimum separation when they touch each other Then A A B VO Vo M R Vo 3GM 28R 6GM 28R 8R B M R VOO C Speed of sphere A at the time of 3GM minimum separation is 7R D Speed of sphere A at the time of

2 A Camat engine operates with a cold reservoir temperature of 200K has an efficiency of 40 it it desires to increase its efficiency to 50 how much degree of increase in temperature should be made to hot reservoir by keeping same temperature for cold reservo O A 25K

d both b and c A jet plane is travelling west at the speed of 1600 km h The voltage difference developed between the ends of the wing having a span of 20 m if the earth s magnetic field at the location has a magnitude of 5 x 10 T and the dip angle is 30 is a 4 1 V c 3 2 V b 2 2 V d 3 8 V with

The maximum value of x In x for 0 x 1 is 1 B A 0 F1 E N C 2e D none of these

A body having velocity 3 km h mass m and moving with collides with a body at rest having mass 2 m and sticks to it The combined mass will begin to move with a velocity A 4 km h B 3 km h C 2 km h 1 km h

lectromagnetic Induction K a c b 32 The north pole of a bar magnet is rapidly introduced into a solenoid at one end say A Which of the following statements correctly depicts the phenomenon taking place No induced emf is developed a No d b The end A of the solenoid behaves like a south pole c The end A of the solenoid behaves like north pole d The end A of the solenoid acquires positive potential 33 An infinitely long cylinder is kept parallel to a uniform magnetic field B directed along positive z axis The direction of induced current on the surface of cylinder as seen from the z axis will be a clockwise of the positive z axis b anticlockwise of the positive z axis c zero d along the magnetic field 34 A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field An emf is induced in the loop if a it is rotated about its axis b it is rotated about a diameter c it is not moved d it is given translational motion in the field a one revolution 1 revolution c 35 When a wire loop is rotated in a magnetic field the direction of induced emf changes in every revolution b 1 2 d 2 revolution MOTIONAL ELECTROMOTIVE FORCE 36 A metallic square loop o ABCD is moving in its own plane with velocity vin a uniform magnetic e field perpendicular to its plane as shown in figure An electric field is induced 000 a in AD but not in BC in BC but not in AD b c d neither in AD nor in BC in both AD and BC 37 A conductor is moving with the velocity v in the magnetic field and induced current is I If the velocity of conductor becomes double the induced current will be a 0 5 I c 21 38 A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil This is because a the magnetic field is constant b the magnetic f field is in the same plane as the circular coil and it may or may not vary c the magnetic field has a perpendicular to the plane of the coil component whose magnitude is decreasing suitably both b and c b 1 51 d 2 51 d 39 A jet plane is travelling west at the speed of 1600 km h The voltage difference developed between the ends of the wing having a span of 20 m if the earth s magnetic field at the location has a magnitude of 5 x 10T and the dip angle is 30 is a 4 1 V c 3 2 V 133 b 2 2 V d 3 8 V 40 A rectangular loop of sides 6 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0 4 T directed normal to the loop The voltage developed across the cut velocity of loop is 2 cm s in a direction normal to the longer side is a 3 8 x 10 v c 2 2 x 10 V a evB 41 In the question number 40 if velocity is normal in the shorter side then the voltage developed is a 2 3 x 10 V b 2 4 x 10 V c 4 8 x 10 V d 1 6 x 10 V 42 The figure shows a wire sliding on two parallel conducting rails placed at a separation 1 A magnetic field B exists in a direction perpendicular to the plane of the rails The force required to keep the wire moving at a constant velocity v will be b c Blv b 4 8 x 10 V d 3 2 x 10 V HoBv 4xl x xxx XL X X X d zero

A charge Q is uniformly distributed over the surface of non conducting disc of radius R The disc rotates about an axis perpendicular to its plane and passing through its centre with an angular velocity w As a result of this rotation a magnetic field of induction B is obtained at the centre of the disc If we keep both the amount of charge placed on the disc and its angular velocity to be constant and vary the radius of the disc then the variation of the magnetic induction at the centre of the disc will be represented by the figure 1 3 B B R R 2 4 B B Medial R Divisions R

Two different types of rubber are found to have the stress strain curve as shown I To absorb vibrations one would prefer rubber A II For manufacturing car tyre one would prefer B I stress Rubber A strain A I II are true B I is true II is false C I is false II is true D I II are false II stress Rubber B strain

A sphere rests between a smooth wall and a smooth wedge of mass M whose inclination to he horizontal is a 60 Mass of sphere is m and its radius is R The wedge initially touches he right wall The vertical side of the wedge is connected to the side wall with the help pring of force constant k n mg R where n is a positive constant Find the minimum value of n for which the sphere may still remain aloft the horizontal surface even if the spring is et go in the position shown and spring is initially compressed Neglect friction Also find he normal reaction between the sphere and the right side vertical wall in critical case

Three equal masses each of 50 g are placed at the corners of a right angled isosceles triangle whose two equal sides are 5 cm each The position of the centre of mass of the system is A x 5 cm y 5 cm cm y 5 cm B X C D x X X 5 3 5 3 5 3 cm y cm y 5 25 3 cm cm els

A cart is moving horizontally along a straight line with constant speed 30 ms 1 A particle is to be fired vertically upwards from the moving cart in such a way that it returns to the cart at the same point from where it was projected after the cart has moved 80 m At what speed relative to the cart must the projectile be fired Take g 10 ms O 10 ms O 10 8ms 1 40 3 ms S 1 None of these

A thin plastic sheet of refractive index 1 6 is used to cover one of the slits of a double slit arrangement The central point on the screen sis now occupied by what would have been the 7th bright fringe before the plastic was used If the wavelength of light is 600 nm what is the thickness in um of the plastic A 7

A swimmer P has a velocity with respect to still water equal to u The velocity of river with respect to ground is v The width of the river is d as shown R P fer u d ff B P Now answer the following questions B 53 V If u 5 m s and v 3m s then the angle with the upstream which the swimmer velocity should make so that the swimmer reaches the directly opposite point B on the other bank zfe u 5 m s 2 v 3m s B qu fau Bu a NH gi fan Bu i t i faufa fenf A 37 C 127 1 D 143

C expe possible set of parameter variations of the parameters in the form of graphs are shown in Column II Mate parameters given in Column I with the graph given in Column II Indicate you darkening the appropriate bubbles of the 4 x 4 matrix given in the ORS Column II Column I A B Potential energy of a simple pendulum y axis as a function of displacement x axis Displacement y axis as a function of time x axis for a one dimensional motion at zero or constant acceleration when the body is moving along the positive x direction S Range of a projectile y axis as a function of its velocity x axis when projected at a fixed angle S The square of the time period y axis of a simple pendulum as a function of its length x axis p q r s 0 X

2 A plane wave of intensity I 0 70 W cm illuminates a sphere with ideal mirror surface The radius of sphere is R 5 0 cm From the standpoint of photon theory find the force that light exerts on the sphere R

1 What is a 2 Name a disease caused by the lack of iron in food 3 What is a communicable disease 4 Which diseases are caused by eating contaminated food 5 Name three diseases for which you have been vaccinated rient DAY F Answer these questions 1 How do houseflies spread disease 2 What precautions would you take to check the spread of malaria 3 Explain two ways of controlling communicable diseases 4 Which steps would you take to prevent the spread of germs from a sick p 5 What is meant by pasteurization of milk 6 Raju has bleeding gums and swollen joints Name the disease he is suffe What is the cause and remedy of this disease

A polarizer analyser set is adjusted such that the intensity of light coming out of the analyser is just 10 of the original intensity Assuming that the polarizer analyser set does not absorb any light the angle by which the analyser need to be rotated further to reduce the output intensity to be zero is 1 18 4 2 71 6 3 90 4 45

Objective NCERT P The ntact 48 A metal conductor of length 1 m rotates vertically about one of its ends with an angular veloc 5 rad s If the horizontal component of ear magnetic field is 0 2 x 10 T then the emf develope between the ends of the conductor is a 5 V b 5 mV c 50 V d 50 mV with 352 tha 49 A rod of length I rotates with a uniform s velocity to about an axis pain Betron FR 2 C In

b Inflated balloon Plastic disc with hole Air cushion a 5 13 Some ways of reducing friction a Ball bearings placed between moving parts of a machine b Compressed cushion of air between surfaces in relative motion

A boat is moving towards east with velocity 4 m s with respect to still water and river is flowing towards north with velocity 2 m s and the wind is blowing towards north with velocity 6 m s The direction of the flag blown over the wind hoisted on the boat is O north west O south east Otan 1 2 with east north

For the system shown in figure if velocity of B at certain instant is 2m s in downward direc then velocity of A at this instant is 3 m s in downward direction 3 m s in upward direction O 6 m s in upward direction 9 m s in upward direction 2 1000 O B

c 53 In a uniform magnetic field B a wire in the form of a semicircle of radius r rotates about the diameter of the circle with angular frequency The axis 59 of rotation is perpendicular to the field If the total resistance of the circuit is R the mean power generated per period of rotation is a c Bir 2R Baru 2R b d Bar 8R Biro 8R and 20 tur 60

2 Look at the following pictures and write a few lines on how the structure shape des each case is used to reduce increase friction grip and the need to do so LO 4 60 a b SP

3 A particle of mass 3 gm moves along the x axis and is attracted towards the origin by a force whose magnitude is numerically equal to to 12 times the instantaneous displacement from the origin The particle is also subjected to a damping force which brings it to the origin in minimum time and whose magnitude is 12 times the instantaneous speed If it is initially at rest at x 10 cm which one of the following equations gives the particle s position at a later time t a 10 40t e 4t b 10 20t e c 10 e t cos 4t d 10 e t sin 4t 2t

A circular copper disc 10 cm in diameter rotates at 1800 revolution per minute about an axis through E its centre and at right angles to disc A uniform field of induction B of 1 Wb mis perpendicular to disc What potential difference is developed between the axis of the disc and the rim 5 a 0 023 V c 23 V b 0 23 V d 230 V